'Constructor.
Args:
template: A Python dict-interpolation string.
prolog: written before the per-record output.
epilog: written after the per-record output.
mode: one of the following, default is \'text\'
text: text file mode, newlines between records.
nonewline: text file mode, no added newlines.
binary: binary file mode, no added newlines.'

def __init__(self, template, prolog=None, epilog=None, mode='text', name=''):

    if (mode not in self.VALID_MODES):
        raise bulkloader_errors.InvalidConfiguration(('simpletext    mode    must    be    one    of    "%s".    (In    transformer    name    %s.)' % ('",    "'.join(self.VALID_MODES), name)))
    self.template = template
    self.prolog = prolog
    self.epilog = epilog
    self.mode = mode
    self.export_file_pointer = None
