This change allows tuples to be passed as the prefix/suffix argument to the
`str.startswith()` and `str.endswith()` methods. The methods will return
`True` if the string starts/ends with any of the prefixes/suffixes in the
tuple.
Also adds full support for the `start` and `end` arguments to both methods
for compatibility with CPython.
Tests have been updated for the new behaviour.
Signed-off-by: Glenn Moloney <glenn.moloney@gmail.com>
eb45d97898