When a module is imported, after the local and global checks within the current program, the imported module will be examined for the called object as well (prior to checking the built-ins). The problem with this is that, unless the called object is explicitly identified with the dot nomenclature, an error will still be generated.
In the following screenshot, we see how the dot nomenclature works:
In this case, we attempt to calculate the square root of a number. Since this operation is unknown to the default Python interpreter, an error is generated. However, if we import the math library in line 2, and then attempt to perform the calculation again, we get an answer.
Note that we explicitly told Python that the square root function is to be found in the math library by using the math.sqrt() command. This is the dot nomenclature that we talked about earlier; the dot indicates that the sqrt() function can be found in the math library. We will see many other examples of this as we discuss programming further, so while it may not make sense right now, hopefully more examples will help.