human
Write me a the Python program you requested given the following:
Complete the below
def importConditions(fileName, returnFieldNames=False, selection=''):

    ''''Imports a list of conditions from an .xlsx, .csv, or .pkl file
    The output is suitable as an input to :class:`TrialHandler`
    `trialTypes` or to :class:`MultiStairHandler` as a `conditions` list.
    If `fileName` ends with:
    - .csv:  import as a comma-separated-value file
    (header + row x col)
    - .xlsx: import as Excel 2007 (xlsx) files.
    No support for older (.xls) is planned.
    - .pkl:  import from a pickle file as list of lists
    (header + row x col)
    The file should contain one row per type of trial needed and one column
    for each parameter that defines the trial type. The first row should give
    parameter names, which should:
    - be unique
    - begin with a letter (upper or lower case)
    - contain no spaces or other punctuation (underscores are permitted)
    `selection` is used to select a subset of condition indices to be used
    It can be a list/array of indices, a python `slice` object or a string to
    be parsed as either option.
    e.g.:
    - "1,2,4" or [1,2,4] or (1,2,4) are the same
    - "2:5"       # 2, 3, 4 (doesn\'t include last whole value)
    - "-10:2:"    # tenth from last to the last in steps of 2
    - slice(-10, 2, None)  # the same as above
    - random(5) * 8  # five random vals 0-8'
    '''
assistant
#Here is the Python program you requested.
    def _assertValidVarNames(fieldNames, fileName):
        'screens    a    list    of    names    as    candidate    variable    names.    if    all\n                                names    are    OK,    return    silently;    else    raise    ImportError    with    msg\n                                '
        if (not all(fieldNames)):
            msg = 'Conditions    file    %s:    Missing    parameter    name(s);    empty    cell(s)    in    the    first    row?'
            raise ImportError((msg % fileName))
        for name in fieldNames:
            (OK, msg) = isValidVariableName(name)
            if (not OK):
                msg = msg.replace('Variables', 'Parameters    (column    headers)')
                raise ImportError(('Conditions    file    %s:    %s%s"%s"' % (fileName, msg, (os.linesep * 2), name)))
    if (fileName in ['None', 'none', None]):
        if returnFieldNames:
            return ([], [])
        return []
    if (not os.path.isfile(fileName)):
        msg = 'Conditions    file    not    found:    %s'
        raise ImportError((msg % os.path.abspath(fileName)))
    def pandasToDictList(dataframe):
        'Convert    a    pandas    dataframe    to    a    list    of    dicts.\n                                This    helper    function    is    used    by    csv    or    excel    imports    via    pandas\n                                '
        trialsArr = dataframe.to_records(index=False)
        if (trialsArr.shape == ()):
            trialsArr = trialsArr[np.newaxis]
        fieldNames = trialsArr.dtype.names
        _assertValidVarNames(fieldNames, fileName)
        trialList = []
        for (trialN, trialType) in enumerate(trialsArr):
            thisTrial = {}
            for (fieldN, fieldName) in enumerate(fieldNames):
                val = trialsArr[trialN][fieldN]
                if isinstance(val, basestring):
                    if (val.startswith('[') and val.endswith(']')):
                        val = eval(val)
                elif (type(val) == np.string_):
...