- at least one of ``x`` or ``y`` must be nonzero
- ``modulo`` must be nonzero and have at most 'precision' digits
- The result of ``Context.power(x, y, modulo)`` is identical to the result
- that would be obtained by computing ``(x**y) % modulo`` with unbounded
- precision, but is computed more efficiently. It is always exact.
+ The value resulting from ``Context.power(x, y, modulo)`` is
+ equal to the value that would be obtained by computing ``(x**y)
+ % modulo`` with unbounded precision, but is computed more
+ efficiently. The exponent of the result is zero, regardless of
+ the exponents of ``x``, ``y`` and ``modulo``. The result is
+ always exact.
.. method:: quantize(x, y)