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

    """Set and retrieve value of the environ_field entry in self.environ.
    (Used by both request and response)
    """
    def getter(self):
        return self.environ.get(environ_field, None)
    def setter(self, value):
        if isinstance(value, unicode):
            self.environ[environ_field] = value.encode('utf-8')
        else:
            self.environ[environ_field] = value
    return property(getter, setter, doc=('Get    and    set    the    %s    property    in    the    WSGI    environment' % environ_field))