'output_file
file object for output
base64_attrs
list of attribute types to be base64-encoded in any case
cols
Specifies how many columns a line may have before it\'s
folded into many lines.
line_sep
String used as line separator'

def __init__(self, output_file, base64_attrs=None, cols=76, line_sep='\n'):

    self._output_file = output_file
    self._base64_attrs = list_dict([a.lower() for a in (base64_attrs or [])])
    self._cols = cols
    self._line_sep = line_sep
    self.records_written = 0
