human
Complete this python program:
def _header_property(header):
assistant
#Here is the Python program you requested.

    """Set and retrieve the value of self.headers[header]
    (Used by both request and response)
    If a value of None is given, the header is deleted.
    :param header: name of the header, e.g. "Content-Length"
    """
    def getter(self):
        return self.headers.get(header, None)
    def setter(self, value):
        self.headers[header] = value
    return property(getter, setter, doc=('Retrieve    and    set    the    %s    header' % header))