Python EOS account name converter from/to string

py_eos_account_conv.py

eos_charmap = ".12345abcdefghijklmnopqrstuvwxyz"

def eos_account_to_string(num):
    mask = 0xF800000000000000
    out = ""
    for i in range(0, 13):
        if num == 0: return out

        indx = (num & mask) >> (60 if i == 12 else 59)
        out += eos_charmap[indx]
        num <<= 5

    return out


def string_to_eos_account(account):
    if len(account) > 13:
        raise ValueError("Account name too long")

    num = 0
    n = min(len(account), 12)
    for i in range(0, n):
        num <<= 5
        num |= eos_charmap.index(account[i]); 

    num <<= 4 + 5*(12 - n)
    if len(account) == 13:
        v = eos_charmap.index(account[12])
        if v > 0x0F:
            raise ValueError("thirteenth character in name cannot be a letter that comes after j")
        num |= v
        
    return num