def get_min(value_type, values):
    """ Returns the minimum value of the input.  Ignores unknown values, if
        no values found besides unknown it will just return 'None'

        Inputs:
          - value_type - one of integer, float, string, timestap
          - dictionary or list of string values
        Outputs:
          - the single minimum value of the appropriate type

        Test Coverage:
          - complete via test harness

    """
    assert value_type in ['integer', 'float', 'string', 'timestamp', 'unknown', None]

    known_vals = []
    for val in values:
        if not typer.is_unknown(val):
            try:
                if value_type == 'integer':
                    known_vals.append(int(val))
                elif value_type == 'float':
                    known_vals.append(float(val))
                else:
                    known_vals.append(val)
            except __HOLE__:
                pass                       # ignore invalid values

    # next return the minimum value
    try:
        return str(min(known_vals))
    except ValueError:
        return None
dataset/ETHPy150Open kenfar/DataGristle/gristle/field_misc.py/get_min