This is one of the cases in which math notation and python are very different. If you say this in python:
s (1 - s)
what you are saying is that s is a function and you are calling it with the argument (1 - s). In this case, s is not a function, so that will not end well. If what you were intending to do is multiply the two operands, then the way to say that in python is this:
s * (1 - s)
See the difference? You need to put an operator between the two operands.