import re


def substitute(dict_, source):
    """ Perform re.sub with the patterns in the given dict
    Args:
      dict_: {pattern: repl}
      source: str
    """
    d_esc = (re.escape(k) for k in dict_.keys())
    pattern = re.compile('|'.join(d_esc))
    return pattern.sub(lambda x: dict_[x.group()], source)