def METHOD_NAME(
    real_fields, imaginary_fields, time_freq_unit=None, server=None
):
    """Create a fields container with two fields (real and imaginary) by time set.
    If the inputs for the fields are dictionaries, this method sets the time frequency
    support with the correct unit if needed.
    Parameters
    ----------
    real_fields : Dictionary(time_int_key : Field) or list of Field
        Dictionary or list of field entities to add to the fields container.
    imaginary_fields : Dictionary(time_int_key : Field) or list of Field
        Dictionary or list of field entities to add to the fields container.
    time_freq_unit : str , optional
        Unit of the time frequency support, which is taken into account if
        the field's attribute has a dictionary type.
    server : ansys.dpf.core.server, optional
        Server with the channel connected to the remote or local instance.
        The default is ``None``, in which case an attempt is made to use the
        global server.
    Returns
    -------
    fields_container : FieldsContainer
        Fields container containing two fields (real and imaginary) by time step.
    """
    if not isinstance(real_fields, dict) and not isinstance(real_fields, list):
        raise dpf_errors.InvalidTypeError("dictionary/list", "real_fields")
    if not isinstance(imaginary_fields, dict) and not isinstance(imaginary_fields, list):
        raise dpf_errors.InvalidTypeError("dictionary/list", "imaginary_fields")
    errorString = "Both real_fields and imaginary_fields must have the same type (list or dict)"
    if isinstance(real_fields, dict):
        if not isinstance(imaginary_fields, dict):
            raise dpf_errors.DpfValueError(errorString)
    elif isinstance(real_fields, list):
        if not isinstance(imaginary_fields, list):
            raise dpf_errors.DpfValueError(errorString)
    fc = FieldsContainer(server=server)
    fc.labels = ["time", "complex"]
    i = 0
    # dict case
    if isinstance(real_fields, dict):
        time_freq = []
        for field_key in real_fields:
            fc.add_field({"time": i + 1, "complex": 0}, real_fields[field_key])
            time_freq.append(field_key)
            i += 1
        i = 0
        im_time_freq = []
        for field_key in imaginary_fields:
            fc.add_field({"time": i + 1, "complex": 1}, imaginary_fields[field_key])
            im_time_freq.append(field_key)
            i += 1
        time_freq_field = fields_factory.create_scalar_field(
            len(real_fields), locations.time_freq, server=server
        )
        time_freq_field.append(time_freq, 1)
        time_freq_field.unit = time_freq_unit
        im_time_freq_field = fields_factory.create_scalar_field(
            len(imaginary_fields), locations.time_freq, server=server
        )
        im_time_freq_field.append(im_time_freq, 1)
        im_time_freq_field.unit = time_freq_unit
        time_freq_support = TimeFreqSupport(server=server)
        time_freq_support.time_frequencies = time_freq_field
        time_freq_support.complex_frequencies = im_time_freq_field
        fc.time_freq_support = time_freq_support
    # list case
    if isinstance(real_fields, list):
        for field in real_fields:
            fc.add_field({"time": i + 1, "complex": 0}, field)
            i += 1
        i = 0
        for field in imaginary_fields:
            fc.add_field({"time": i + 1, "complex": 1}, field)
            i += 1
    return fc