FileInput([files[, inplace[, backup]]], *, mode=None, openhook=None)
Class FileInput is the implementation of the module; its methods
filename(), lineno(), fileline(), isfirstline(), isstdin(), fileno(),
nextfile() and close() correspond to the functions of the same name
in the module.
In addition it has a readline() method which returns the next
input line, and a __getitem__() method which implements the
sequence behavior. The sequence must be accessed in strictly
sequential order; random access and readline() cannot be mixed.