Returns a dictionary from HTTP header text.

        >>> h = HTTPHeaders.parse("Content-Type: text/html\\r\\nContent-Length: 42\\r\\n")
        >>> sorted(h.items())
        [('Content-Length', '42'), ('Content-Type', 'text/html')]

        .. versionchanged:: 5.1

           Raises `HTTPInputError` on malformed headers instead of a
           mix of `KeyError`, and `ValueError`.

def parse(cls, headers: str) -> "HTTPHeaders":
        """Returns a dictionary from HTTP header text.

        >>> h = HTTPHeaders.parse("Content-Type: text/html\\r\\nContent-Length: 42\\r\\n")
        >>> sorted(h.items())
        [('Content-Length', '42'), ('Content-Type', 'text/html')]

        .. versionchanged:: 5.1

           Raises `HTTPInputError` on malformed headers instead of a
           mix of `KeyError`, and `ValueError`.

        """
        h = cls()
        for line in _CRLF_RE.split(headers):
            if line:
                h.parse_line(line)
        return h