def _evaluate_usecols(usecols, names):
 if callable(usecols):
  return set([i for (i, name) in enumerate(names) if usecols(name)])
 return usecols

def _evaluate_usecols ( usecols , names ) : if callable ( usecols ) : return set ( [ i for ( i , name ) in enumerate ( names ) if usecols ( name ) ] ) return usecols
check whether or not the usecols parameter is a callable .