human
Complete this python program:
def get_canonical_form_slice(theslice, length):
assistant
#Here is the Python program you requested.

    """Given a slice [start:stop:step] transform it into a canonical form
    that respects the conventions imposed by python and numpy.
    In a canonical form a slice is represented by a canonical form slice,
    in which 0 <= start <= stop <= length and step > 0, and a flag which says
    if the resulting set of numbers needs to be reversed or not.
    """
    from theano.tensor import switch, lt, ge, sgn
    if isinstance(theslice, slice):
        def analyze(x):
            try:
                x_constant = get_scalar_constant_value(x)
                is_constant = True
            except theano.tensor.NotScalarConstantError:
                x_constant = theano.tensor.extract_constant(x)
                is_constant = False
            return (x_constant, is_constant)
        (start, is_start_constant) = analyze(theslice.start)
        (stop, is_stop_constant) = analyze(theslice.stop)
        (step, is_step_constant) = analyze(theslice.step)
        (length, is_length_constant) = analyze(length)
        if (step is None):
            step = 1
            is_step_constant = True
        if (step == 1):
            is_start_0 = ((start is None) or (start == 0) or (is_start_constant and is_length_constant and (start < 0) and ((start + length) <= 0)))
            is_stop_length = ((stop is None) or (stop in [length, sys.maxsize]) or (is_stop_constant and is_length_constant and (stop >= length)))
            if is_start_0:
                if is_stop_length:
                    return (slice(0, length, 1), 1)
                if (is_stop_constant and (stop >= 0)):
                    return (slice(0, switch(lt(stop, length), stop, length), 1), 1)
                stop_plus_len = (stop + length)
                stop = switch(lt(stop, 0), switch(lt(stop_plus_len, 0), 0, stop_plus_len), switch(lt(stop, length), stop, length))
                return (slice(0, stop, 1), 1)
            elif is_stop_length:
                if (is_start_constant and (start >= 0)):
                    return (slice(switch(lt(start, length), start, length), length, 1), 1)
                start_plus_len = (start + length)
                start = switch(lt(start, 0), switch(lt(start_plus_len, 0), 0, start_plus_len), switch(lt(start, length), start, length))
                return (slice(start, length, 1), 1)
        if is_step_constant:
            assert (step != 0)
            if (step > 0):
  ...