'The WSGI I{start_response} callable.  The given values are saved until
they are needed to generate the response.
This will be called in a non-I/O thread.'

def startResponse(self, status, headers, excInfo=None):

    if (self.started and (excInfo is not None)):
        reraise(excInfo[1], excInfo[2])
    if (not isinstance(status, str)):
        raise TypeError(('status    must    be    str,    not    %r    (%s)' % (status, type(status).__name__)))
    if isinstance(headers, list):
        pass
    elif isinstance(headers, Sequence):
        warn(('headers    should    be    a    list,    not    %r    (%s)' % (headers, type(headers).__name__)), category=RuntimeWarning)
    else:
        raise TypeError(('headers    must    be    a    list,    not    %r    (%s)' % (headers, type(headers).__name__)))
    for header in headers:
        if isinstance(header, tuple):
            pass
        elif isinstance(header, Sequence):
            warn(('header    should    be    a    (str,    str)    tuple,    not    %r    (%s)' % (header, type(header).__name__)), category=RuntimeWarning)
        else:
            raise TypeError(('header    must    be    a    (str,    str)    tuple,    not    %r    (%s)' % (header, type(header).__name__)))
        if (len(header) != 2):
            raise TypeError(('header    must    be    a    (str,    str)    tuple,    not    %r' % (header,)))
        for elem in header:
            if (not isinstance(elem, str)):
                raise TypeError(('header    must    be    (str,    str)    tuple,    not    %r' % (header,)))
    self.status = status
    self.headers = headers
    return self.write
