How to use the fmpy.util._is_string function in FMPy

setter = getattr(fmu, 'setInt32')
        else:
            setter = getattr(fmu, 'set' + variable.type)

        # convert Boolean values
        if variable.type == 'Boolean':
            if isinstance(value, str):
                if value.lower() not in ['true', 'false']:
                    raise Exception('The start value "%s" for variable "%s" could not be converted to Boolean' %
                                    (value, variable.name))
                else:
                    value = value.lower() == 'true'

        # convert the type
        if variable.shape:
            if _is_string(value):
                value = value.split()
            value = list(map(lambda e: variable._python_type(e), value))
            if len(value) != np.prod(variable.shape):
                raise ArgumentError('The start value for variable "%s" must have %d elements but has %d.' %
                                    (variable.name, np.prod(variable.shape), len(value)))
        else:
            value = [variable._python_type(value)]

        setter([vr], value)

    if len(start_values) > 0:
        raise Exception("The start values for the following variables could not be set because they don't exist: " +
                        ', '.join(start_values.keys()))

def supported_platforms(filename):
    """ Get the platforms supported by the FMU without extracting it

    Parameters:
        filename    filename of the FMU, directory with extracted FMU or file like object

    Returns:
        platforms   a list of supported platforms supported by the FMU
    """

    from .util import _is_string

    # get the files within the FMU
    if _is_string(filename) and os.path.isdir(filename):  # extracted FMU
        names = []
        for dirpath, _, filenames in os.walk(filename):
            for name in filenames:
                abspath = os.path.join(dirpath, name)
                names.append(os.path.relpath(abspath, start=filename).replace('\\', '/'))
    else:  # FMU as path or file like object
        import zipfile
        with zipfile.ZipFile(filename, 'r') as zf:
            names = zf.namelist()

    platforms = []

    # check for the C-sources
    for name in names:
        head, tail = os.path.split(name)
        if head == 'sources' and tail.endswith('.c'):

returns:
        model_description   a ModelDescription object
    """

    import zipfile
    from lxml import etree
    import os
    from .util import _is_string

    # remember the original filename
    _filename = filename

    if _is_string(filename) and os.path.isdir(filename):  # extracted FMU
        filename = os.path.join(filename, 'modelDescription.xml')
        tree = etree.parse(filename)
    elif _is_string(filename) and os.path.isfile(filename) and filename.lower().endswith('.xml'):  # XML file
        tree = etree.parse(filename)
    else:  # FMU as path or file like object
        with zipfile.ZipFile(filename, 'r') as zf:
            xml = zf.open('modelDescription.xml')
            tree = etree.parse(xml)

    root = tree.getroot()

    fmiVersion = root.get('fmiVersion')

    if not fmiVersion.startswith('3.0') and fmiVersion not in ['1.0', '2.0']:
        raise Exception("Unsupported FMI version: %s" % fmiVersion)

    if validate:

        module_dir, _ = os.path.split(__file__)

def read_build_description(filename, validate=True):

    import zipfile
    from lxml import etree
    import os
    from .util import _is_string

    if _is_string(filename) and os.path.isdir(filename):  # extracted FMU
        filename = os.path.join(filename, 'sources/buildDescription.xml')
        if not os.path.isfile(filename):
            return []
        tree = etree.parse(filename)
    elif _is_string(filename) and os.path.isfile(filename) and filename.lower().endswith('.xml'):  # XML file
        if not os.path.isfile(filename):
            return []
        tree = etree.parse(filename)
    else:  # FMU as path or file like object
        with zipfile.ZipFile(filename, 'r') as zf:
            if 'sources/buildDescription.xml' not in zf.namelist():
                return []
            xml = zf.open('sources/buildDescription.xml')
            tree = etree.parse(xml)

    root = tree.getroot()

    fmi_version = root.get('fmiVersion')

    if fmi_version is None or not fmi_version.startswith('3.0'):
        raise Exception("Unsupported fmiBuildDescription version: %s" % fmi_version)

def read_build_description(filename, validate=True):

    import zipfile
    from lxml import etree
    import os
    from .util import _is_string

    if _is_string(filename) and os.path.isdir(filename):  # extracted FMU
        filename = os.path.join(filename, 'sources/buildDescription.xml')
        if not os.path.isfile(filename):
            return []
        tree = etree.parse(filename)
    elif _is_string(filename) and os.path.isfile(filename) and filename.lower().endswith('.xml'):  # XML file
        if not os.path.isfile(filename):
            return []
        tree = etree.parse(filename)
    else:  # FMU as path or file like object
        with zipfile.ZipFile(filename, 'r') as zf:
            if 'sources/buildDescription.xml' not in zf.namelist():
                return []
            xml = zf.open('sources/buildDescription.xml')
            tree = etree.parse(xml)

    root = tree.getroot()