def number(self, num):
        try:
            if num.startswith('$'):
                # hexadecimal
                return self._constrain(int(num[1:], 16))

            elif num.startswith('+'):
                # decimal
                return self._constrain(int(num[1:], 10))

            elif num.startswith('%'):
                # binary
                return self._constrain(int(num[1:], 2))

            elif num in self.labels:
                # label name
                return self.labels[num]

            else:
                matches = re.match('^([^\s+-]+)\s*([+\-])\s*([$+%]?\d+)$', num)
                if matches:
                    label, sign, offset = matches.groups()

                    if label not in self.labels:
                        raise KeyError("Label not found: %s" % label)

                    base = self.labels[label]
                    offset = self.number(offset)

                    if sign == '+':
                        address = base + offset
                    else:
                        address = base - offset

                    return self._constrain(address)

                else:
                    return self._constrain(int(num, self.radix))

        except ValueError:
            raise KeyError("Label not found: %s" % num)
Parse a string containing a label or number into an address.
dataset/ETHPy150Open mnaberez/py65/py65/utils/addressing.py/AddressParser.number