Count trailing and leading zeroes in Python

count_lead_trail_zeroes.py

def count_lead_and_trail_zeroes(d):
    """Count the number of leading and trailing zeroes in an integer."""
    b = "{:064b}".format(d)
    try:
        return as_str.index("1"), 63 - as_str.rindex("1")
    except ValueError:
        return 64, 64

def count_lead_and_trail_zeroes(d):
    # https://graphics.stanford.edu/~seander/bithacks.html#ZerosOnRightLinear
    if d:
        v = (d ^ (d - 1) >> 1)  # Set v's trailing 0s to 1s and zero rest
        trailing = 0
        while v:
            v >>= 1
            trailing += 1

        leading = 64
        v = d
        while v:
            v >>= 1
            leading -= 1
        return leading, trailing
    return 64, 64

I know it is a gist from 2016, but since it shows up in google search I would like to clarify that the first function probably should have as_str replaced with b because as_str is undefined.

this is how it would look like:

def count_lead_and_trail_zeroes(d):
"""Count the number of leading and trailing zeroes in an integer."""
b = "{:064b}".format(d)
try:
return b.index("1"), 63 - b.rindex("1")
except ValueError:
return 64, 64