class StringIO([buffer])

When a StringIO object is created, it can be initialized to an existing
string by passing the string to the constructor. If no string is given,
the StringIO will start empty.

The StringIO object can accept either Unicode or 8-bit strings, but
mixing the two may take some care. If both are used, 8-bit strings that
cannot be interpreted as 7-bit ASCII (that use the 8th bit) will cause
a UnicodeError to be raised when getvalue() is called.

str(object) -> string

Return a nice string representation of the object.
If the argument is a string, the return value is the same object.