parameters: (self)
docstring: Returns underlying file descriptor if one exists.
  
          An IOError is raised if the IO object does not use a file descriptor.
docstring_summary: Returns underlying file descriptor if one exists.
docstring_tokens: Returns underlying file descriptor if one exists .
function: def fileno(self):
          """Returns underlying file descriptor if one exists.
  
          An IOError is raised if the IO object does not use a file descriptor.
          """
          self._unsupported("fileno")
function_tokens: def fileno ( self ) : self . _unsupported ( "fileno" )