@classmethod
def normalize(cls, addrs, default_encoding='utf-8'):
    """
        Normalize one or more addresses of the form string, tuple or
        `EmailContact`) to `EmailContact`s.
        """
    normalized = []
    for addr in addrs:
        if isinstance(addr, cls):
            addr = addr
        elif isinstance(addr, tuple):
            addr = cls(*addr)
        else:
            addr = cls(addr)
        normalized.append(addr)
    return normalized
