[Python] Formating strings and converting between representations

I am working on a library in which I serialize data. The issue is when I tried to visualize the serialization, I get different results from if I had no formatting to the serialization.

# ansi colour codes
g='\033[0;32m'
lp='\033[1;35m'
lc='\033[1;36m'
y='\033[1;33m'
r='\033[0m'
bb='\033[1;94m'
gr='\033[1;90m'
bc='\033[1;96m'
re='\033[1;31m'
rb='\033[1;91m'
w='\033[1;97m'

class Signature:
def __init__(self, r_x, value):
self.r_x = r_x
self.value = value

def der(self, display=False):
if not display:
rxbin = self.r_x.to_bytes(32, 'big')
# removing all null bytes
rxbin = rxbin.lstrip(b"\x00")
# if rxbin has high bit add \x00
if rxbin[0] & 0x80:
rxbin = b'\x00' + rxbin
result = bytes([2, len(rxbin)]) + rxbin
sigbin = self.value.to_bytes(32, 'big')
sigbin = sigbin.lstrip(b"\x00")
if sigbin[0] & 0x80:
sigbin = b'\x00' + sigbin
result += bytes([2, len(sigbin)]) + sigbin
return bytes([0x30, len(result)]) + result
else:
rxbin = self.r_x.to_bytes(32, 'big')
# removing all null bytes
rxbin = rxbin.lstrip(b"\x00")
# if rxbin has high bit add \x00
if rxbin[0] & 0x80:
rxbin = b'\x00' + rxbin

r_x_value = lp + f"{hex(int.from_bytes(rxbin, 'big'))}".lstrip("0x") + r
r_x_length = lc + f"{hex(len(rxbin))}".lstrip('0x') + r
r_prefxbyte = re + f"02" + r
# b'\x02'
result = bytes([2, len(rxbin)]) + rxbin

sigbin = self.value.to_bytes(32, 'big')
sigbin = sigbin.lstrip(b"\x00")
if sigbin[0] & 0x80:
sigbin = b'\x00' + sigbin
result += bytes([2, len(sigbin)]) + sigbin


sig_value = y + f"{hex(int.from_bytes(sigbin, 'big'))}".lstrip("0x") + r
sig_length = gr + f"{hex(len(sigbin))}".lstrip('0x') + r
sig_prefxbyte = bb + "02" + r


prefix = g + f"{hex(0x30)}".lstrip("0x") + r + w + f"{hex(len(result))}".lstrip("0x") + r

print()
print("Distinguished encoding representation for signatures in hex base. der signature serialization:")
print()
print(prefix + r_prefxbyte +r_x_length + r_x_value + sig_prefxbyte + sig_length+ sig_value )
print()
print("key:")
print(g + "Signature prefix "+ r )
print(w+ "Length of complete signature" + r)
print(y + "signature value " + r )
print(gr + "signature length " + r )
print(bb + "signature prefix " + r )

print(lc + "r_x length " + r )
print(lp + "r_x value " + r )
print(re + "r_x prefix " + r )
print()


where I have added the if-else statement in .der() method to help with visualizing the serialization.

using the given values from here, i.e.

r = 0x37206a0610995c58074999cb9767b87af4c4978db68c06e8e6e81d282047a7c6
s = 0x8ca63759c1157ebeaec0d03cecca119fc9a75bf8e6d0fa65c841c8e2738cdaec


I yield the correct serialization when using the original .der() method (without display)

3045022037206a0610995c58074999cb9767b87af4c4978db68c06e8e6e81d282047a7c60221008ca63759c1157ebeaec0d03cecca119fc9a75bf8e6d0fa65c841c8e2738cdaec


but my colorized version, is slightly different:

3045022037206a0610995c58074999cb9767b87af4c4978db68c06e8e6e81d282047a7c602218ca63759c1157ebeaec0d03cecca119fc9a75bf8e6d0fa65c841c8e2738cdaec


where all thats different is a missing 00 between the signature value length, and the actual signature value. i.e

correct serialization: 3045022037206a0610995c58074999cb9767b87af4c4978db68c06e8e6e81d282047a7c60221008ca63759c1157ebeaec0d03cecca119fc9a75bf8e6d0fa65c841c8e2738cdaec

colorised serialization with missing 00: 3045022037206a0610995c58074999cb9767b87af4c4978db68c06e8e6e81d282047a7c602218ca63759c1157ebeaec0d03cecca119fc9a75bf8e6d0fa65c841c8e2738cdaec

Can anyone see what it is I am doing wrong? I have check and double checked the implementation and cannot see why my colorised printed version would be different than the version produced by the original .der() method.

Here is a screenshot of the goal of this display option

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