Despite the lack of support that Fortran gives to checking function call interfaces, do not shy away from using them. User-defined functions (and, as we will see in a future lesson, subroutines) are one of the major reasons why it is possible to write large programs containing thousands (and sometimes millions) of lines of code.
A programmer only needs to know what a function does, and can ignore how it does it, once the function is written and documented. In other words, it should be possible to use a well-written function by looking at only the comments and the argument list.
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