def determine_instrument_type_from_blockette(parser, channel_id):
    """
    Determines type of instrument used to record a channel with provided
    channel_id.

    :type parser: obspy.io.xseed.parser.Parser
    :param parser: Parser object parsed from Full SEED or dataless or
        StationXML.
    :type channel_id: str
    :param channel_id: Channel_id object generated by obspy.trace.Trace.id
    :rtype: str
    :return: Returns str determining the type of instrument
    """
    return translate_unit_to_instrument_type(determine_unit_from_blockette(parser, channel_id))


def determine_unit_from_blockette(parser, channel_id):
    """
    Determines the unit used to record a channel with provided
    channel_id.

    :type parser: obspy.io.xseed.parser.Parser
    :param parser: Parser object parsed from Full SEED or dataless or
        StationXML.
    :type channel_id: str
    :param channel_id: Channel_id object generated by obspy.trace.Trace.id
    :rtype: str
    :return: Returns str containing a real unit name that can be passed to
        translate_unit_to_instrument_type method
        to obtain a str compatible with response removal procedure
    """
    for blkt in parser._select(channel_id):
        if not blkt.id == 52:
            continue

        for bl in parser.blockettes[34]:
            if bl.unit_lookup_code == blkt.units_of_signal_response:
                return bl.unit_name


def determine_instrument_type_from_inventory(inv, channel_id, time):
    """
    Determines type of instrument used to record a channel with provided channel_id at the provided time.

    :type inv: obspy.core.inventory.inventory.Inventory
    :param inv: ObsPy Inventory object parsed from a file
    :type channel_id: str
    :param channel_id: Channel_id object generated by obspy.trace.Trace.id
    :type time: obspy.core.utcdatetime.UTCDateTime
    :param time: time for which the unit should be determined in the inventory (e.g. start time of a trace)
    :rtype: str
    :return: Returns str determining the type of instrument
    """
    return translate_unit_to_instrument_type(determine_unit_from_inventory(inv, channel_id, time))


def determine_unit_from_inventory(inv, channel_id, time):
    """
    Determines unit used to record a channel with provided channel_id at the provided time.

    :type inv: obspy.core.inventory.inventory.Inventory
    :param inv: ObsPy Inventory object parsed from a file
    :type channel_id: str
    :param channel_id: Channel_id object generated by obspy.trace.Trace.id
    :type time: obspy.core.utcdatetime.UTCDateTime
    :param time: time for which the unit should be determined in the inventory (e.g. start time of a trace)
    :rtype: str
    :return: Returns str containing a real unit name that can be passed to
        translate_unit_to_instrument_type method
        to obtain a str compatible with response removal procedure
    """
    resp = inv.get_response(channel_id, time)
    return resp.instrument_sensitivity.input_units


def translate_unit_to_instrument_type(unit_name):
    if unit_name == "M":
        return "DISP"
    elif unit_name == "M/S":
        return "VEL"
    elif unit_name == "M/S**2":
        return "ACC"
    else:
        raise TypeError("Unknown unit code ", unit_name)


def translate_instrument_type_to_unit(unit_type):
    if unit_type == "DISP":
        return "M"
    elif unit_type == "VEL":
        return "M/S"
    elif unit_type == "ACC":
        return "M/S**2"
    else:
        raise TypeError("Unknown unit code ", unit_type)