def paz_to_sacpz_string(paz, instrument_sensitivity):
    """
    Returns SACPZ ASCII text representation of Response.

    :type paz: :class:`PolesZerosResponseStage`
    :param paz: Poles and Zeros response information
    :type instrument_sensitivity: :class:`InstrumentSensitivity`
    :param paz: Overall instrument sensitivity of response
    :rtype: str
    :returns: Textual SACPZ representation of poles and zeros response stage.
    """
    # assemble output string
    out = []
    out.append("ZEROS %i" % len(paz.zeros))
    for c in paz.zeros:
        out.append(" %+.6e %+.6e" % (c.real, c.imag))
    out.append("POLES %i" % len(paz.poles))
    for c in paz.poles:
        out.append(" %+.6e %+.6e" % (c.real, c.imag))
    constant = paz.normalization_factor * instrument_sensitivity.value
    out.append("CONSTANT %.6e" % constant)
    return "\n".join(out)