Exceptions are string objects. Two distinct string objects with the
same value are different exceptions. This is done to force programmers
to use exception names rather than their string value when specifying
exception handlers. The string value of all built-in exceptions is
their name, but this is not a requirement for user-defined exceptions
or exceptions defined by library modules.
The following exceptions can be generated by the interpreter or
built-in functions. Except where mentioned, they have an `associated
value' indicating the detailed cause of the error. This may be a
string or a tuple containing several items of information (e.g., an
error code and a string explaining the code).
User code can raise built-in exceptions. This can be used to test an
exception handler or to report an error condition `just like' the
situation in which the interpreter raises the same exception; but
beware that there is nothing to prevent user code from raising an
inappropriate error.
AttributeError