This is a review of previous concepts.
from tx import Tx
from io import BytesIO
from ecc import S256Point, Signature
class Tx(Tx):
def verify_input(self, input_index):
'''Returns whether the input has a valid signature'''
# get the relevant input
# parse the point from the sec format (tx_in.sec_pubkey())
# parse the signature from the der format (tx_in.der_signature())
# get the hash type from the input (tx_in.hash_type())
# get the sig_hash (z)
# use point.verify on the z and signature
pass