fixed flake8 and a few other things

author_bio.html

@@ -1,5 +1,5 @@
 <section data-type="colophon" class="abouttheauthor">
   <h1>About the Author</h1>
   <p>Jimmy Song is a developer of over 20 years, starting his career by reading the Programming Perl 2nd Edition published by the very same publisher as this book. He's been involved in way too many startups and got into Bitcoin full-time in 2014. He's contributed to many different Bitcoin open source projects over the years, including Armory, Bitcoin Core, btcd and pycoin.</p>
-  <p>If you ever meet Jimmy and want him to rant, ask him about Bitcoin, sound money, fasting, carnivory, powerlifting, raising children or cowboy hats.</p>
+  <p>If you ever meet Jimmy and want him to rant, ask him about Bitcoin, sound money, how fiat money makes everything worse, fasting, carnivory, powerlifting, raising children or cowboy hats.</p>
 </section>

code-ch01/answers.py

@@ -119,6 +119,7 @@
 # end::exercise1[]
 '''
 
+
 # tag::answer1[]
 def __ne__(self, other):
     # this should be the inverse of the == operator
@@ -134,6 +135,7 @@ def __ne__(self, other):
 # end::exercise3[]
 '''
 
+
 # tag::answer3[]
 def __sub__(self, other):
     if self.prime != other.prime:
@@ -187,13 +189,13 @@ def __truediv__(self, other):
     # this means:
     # 1/n == pow(n, p-2, p)
     # We return an element of the same class
-    num = self.num * pow(other.num, self.prime-2, self.prime) % self.prime
+    num = self.num * pow(other.num, self.prime - 2, self.prime) % self.prime
     return self.__class__(num, self.prime)
 # end::answer9[]
 
 
 class ChapterTest(TestCase):
-    
+
     def test_apply(self):
         FieldElement.__ne__ = __ne__
         FieldElement.__sub__ = __sub__

code-ch02/answers.py

@@ -64,11 +64,13 @@
 # end::exercise2[]
 '''
 
+
 # tag::answer2[]
 def __ne__(self, other):
     return not (self == other)
 # end::answer2[]
 
+
 '''
 # tag::exercise3[]
 ==== Exercise 3
@@ -87,6 +89,7 @@ def __ne__(self, other):
 # end::exercise7[]
 '''
 
+
 def __add__(self, other):
     if self.a != other.a or self.b != other.b:
         raise TypeError

code-ch03/answers.py

@@ -121,7 +121,7 @@
 Verify whether these signatures are valid:
 
 ```
-P = (0x887387e452b8eacc4acfde10d9aaf7f6d9a0f975aabb10d006e4da568744d06c, 
+P = (0x887387e452b8eacc4acfde10d9aaf7f6d9a0f975aabb10d006e4da568744d06c,
      0x61de6d95231cd89026e286df3b6ae4a894a3378e393e93a0f45b666329a0ae34)
 
 # signature 1
@@ -138,7 +138,7 @@
 # tag::answer6[]
 >>> from ecc import S256Point, N, G
 >>> point = S256Point(
-...     0x887387e452b8eacc4acfde10d9aaf7f6d9a0f975aabb10d006e4da568744d06c, 
+...     0x887387e452b8eacc4acfde10d9aaf7f6d9a0f975aabb10d006e4da568744d06c,
 ...     0x61de6d95231cd89026e286df3b6ae4a894a3378e393e93a0f45b666329a0ae34)
 >>> z = 0xec208baa0fc1c19f708a9ca96fdeff3ac3f230bb4a7ba4aede4942ad003c0f60
 >>> r = 0xac8d1c87e51d0d441be8b3dd5b05c8795b48875dffe00b7ffcfac23010d3a395
@@ -190,9 +190,7 @@
 
 from unittest import TestCase
 
-from ecc import FieldElement, Point, S256Point, ECCTest, G, N
-from random import randint
-from helper import hash256
+from ecc import FieldElement, Point, ECCTest
 
 
 class ChapterTest(TestCase):
@@ -226,7 +224,7 @@ def test_add(self):
                 x3 = FieldElement(x3_raw, prime)
                 y3 = FieldElement(y3_raw, prime)
                 p3 = Point(x3, y3, a, b)
-                self.assertEqual(p1+p2, p3)
+                self.assertEqual(p1 + p2, p3)
         # end::answer3[]
-        
+
         ECCTest.test_add = test_add

code-ch03/ecc.py

@@ -174,7 +174,6 @@ def __add__(self, other):
         if self.x == other.x and self.y != other.y:
             return self.__class__(None, None, self.a, self.b)
 
-
         # Case 2: self.x ≠ other.x
         # Formula (x3,y3)==(x1,y1)+(x2,y2)
         # s=(y2-y1)/(x2-x1)
@@ -271,7 +270,6 @@ def test_on_curve(self):
                 Point(x, y, a, b)  # <1>
     # end::source2[]
 
-
     def test_add(self):
         # tests the following additions on curve y^2=x^3-7 over F_223:
         # (192,105) + (17,56)
@@ -395,6 +393,7 @@ def verify(self, z, sig):
     0x483ada7726a3c4655da4fbfc0e1108a8fd17b448a68554199c47d08ffb10d4b8)
 # end::source10[]
 
+
 class S256Test(TestCase):
 
     def test_order(self):

code-ch04/answers.py

@@ -55,7 +55,7 @@
 
 `0x37206a0610995c58074999cb9767b87af4c4978db68c06e8e6e81d282047a7c6`
 
-* s = 
+* s =
 
 `0x8ca63759c1157ebeaec0d03cecca119fc9a75bf8e6d0fa65c841c8e2738cdaec`
 # end::exercise3[]
@@ -155,9 +155,6 @@
 
 from unittest import TestCase
 
-from ecc import PrivateKey, Signature
-from helper import encode_base58, hash256
-
 import helper
 
 
@@ -169,13 +166,15 @@
 # end::exercise7[]
 '''
 
+
 # tag::answer7[]
 def little_endian_to_int(b):
     '''little_endian_to_int takes byte sequence as a little-endian number.
     Returns an integer'''
     return int.from_bytes(b, 'little')
 # end::answer7[]
 
+
 '''
 # tag::exercise8[]
 ==== Exercise 8
@@ -184,6 +183,7 @@ def little_endian_to_int(b):
 # end::exercise8[]
 '''
 
+
 # tag::answer8[]
 def int_to_little_endian(n, length):
     '''endian_to_little_endian takes an integer and returns the little-endian

code-ch04/ecc.py

@@ -181,7 +181,6 @@ def __add__(self, other):
         if self.x == other.x and self.y != other.y:
             return self.__class__(None, None, self.a, self.b)
 
-
         # Case 2: self.x ≠ other.x
         # Formula (x3,y3)==(x1,y1)+(x2,y2)
         # s=(y2-y1)/(x2-x1)

code-ch04/helper.py

@@ -35,7 +35,7 @@ def encode_base58(s):
         else:
             break
     prefix = b'1' * count
-    num = int(s.hex(), 16)
+    num = int.from_bytes(s, 'big')
     result = bytearray()
     while num > 0:  # <2>
         num, mod = divmod(num, 58)

code-ch05/answers.py

@@ -61,7 +61,6 @@
 '''
 
 
-from io import BytesIO
 from unittest import TestCase
 
 from helper import little_endian_to_int, read_varint
@@ -71,6 +70,7 @@
 
 methods = []
 
+
 '''
 # tag::exercise1[]
 ==== Exercise 1
@@ -99,6 +99,8 @@ def parse(cls, s, testnet=False):
         return cls(version, inputs, None, None, testnet=testnet)
 # end::answer2.1[]
 '''
+
+
 # tag::answer2.2[]
 @classmethod
 def parse(cls, s):
@@ -111,8 +113,11 @@ def parse(cls, s):
     sequence = little_endian_to_int(s.read(4))
     return cls(prev_tx, prev_index, script_sig, sequence)
 # end::answer2.2[]
+
+
 methods.append(parse)
 
+
 '''
 # tag::exercise3[]
 ==== Exercise 3
@@ -137,6 +142,7 @@ def parse(cls, s, testnet=False):
 # end::answer3.1[]
 '''
 
+
 # tag::answer3.2[]
 @classmethod
 def parse(cls, s):
@@ -147,8 +153,11 @@ def parse(cls, s):
     script_pubkey = Script.parse(s)
     return cls(amount, script_pubkey)
 # end::answer3.2[]
+
+
 methods.append(parse)
 
+
 '''
 # tag::exercise4[]
 ==== Exercise 4
@@ -157,6 +166,7 @@ def parse(cls, s):
 # end::exercise4[]
 '''
 
+
 # tag::answer4[]
 @classmethod
 def parse(cls, s, testnet=False):
@@ -172,8 +182,11 @@ def parse(cls, s, testnet=False):
     locktime = little_endian_to_int(s.read(4))
     return cls(version, inputs, outputs, locktime, testnet=testnet)
 # end::answer4[]
+
+
 methods.append(parse)
 
+
 '''
 # tag::exercise6[]
 ==== Exercise 6
@@ -182,6 +195,7 @@ def parse(cls, s, testnet=False):
 # end::exercise6[]
 '''
 
+
 # tag::answer6[]
 def fee(self, testnet=False):
     input_sum, output_sum = 0, 0

code-ch05/ecc.py

@@ -181,7 +181,6 @@ def __add__(self, other):
         if self.x == other.x and self.y != other.y:
             return self.__class__(None, None, self.a, self.b)
 
-
         # Case 2: self.x ≠ other.x
         # Formula (x3,y3)==(x1,y1)+(x2,y2)
         # s=(y2-y1)/(x2-x1)

code-ch05/helper.py

@@ -31,8 +31,8 @@ def encode_base58(s):
         else:
             break
     prefix = b'1' * count
-    # convert from binary to hex, then hex to integer
-    num = int(s.hex(), 16)
+    # convert to big endian integer
+    num = int.from_bytes(s, 'big')
     result = bytearray()
     while num > 0:
         num, mod = divmod(num, 58)

code-ch05/tx.py

@@ -229,6 +229,7 @@ def serialize(self):  # <1>
         return result
     # end::source4[]
 
+
 class TxTest(TestCase):
     cache_file = '../tx.cache'
 

code-ch06/answers.py

@@ -70,15 +70,13 @@
 '''
 
 
-from io import BytesIO
 from unittest import TestCase
 
 import op
 
 from ecc import S256Point, Signature
 from helper import hash160
 from op import encode_num
-from script import Script
 
 
 '''
@@ -89,6 +87,7 @@
 # end::exercise1[]
 '''
 
+
 # tag::answer1[]
 def op_hash160(stack):
     if len(stack) < 1:
@@ -99,6 +98,7 @@ def op_hash160(stack):
     return True
 # end::answer1[]
 
+
 '''
 # tag::exercise2[]
 ==== Exercise 2
@@ -107,6 +107,7 @@ def op_hash160(stack):
 # end::exercise2[]
 '''
 
+
 # tag::answer2[]
 def op_checksig(stack, z):
     if len(stack) < 2:

code-ch06/ecc.py

@@ -181,7 +181,6 @@ def __add__(self, other):
         if self.x == other.x and self.y != other.y:
             return self.__class__(None, None, self.a, self.b)
 
-
         # Case 2: self.x ≠ other.x
         # Formula (x3,y3)==(x1,y1)+(x2,y2)
         # s=(y2-y1)/(x2-x1)

code-ch06/helper.py

@@ -34,8 +34,8 @@ def encode_base58(s):
         else:
             break
     prefix = b'1' * count
-    # convert from binary to hex, then hex to integer
-    num = int(s.hex(), 16)
+    # convert to big endian integer
+    num = int.from_bytes(s, 'big')
     result = bytearray()
     while num > 0:
         num, mod = divmod(num, 58)

code-ch06/script.py

@@ -136,6 +136,7 @@ def evaluate(self, z):
         return True  # <10>
     # end::source5[]
 
+
 class ScriptTest(TestCase):
 
     def test_parse(self):