;Task:
Demonstrate the different syntax and semantics provided for calling a function. 


This may include:
:*   Calling a function that requires no arguments
:*   Calling a function with a fixed number of arguments
:*   Calling a function with [[Optional parameters|optional arguments]]
:*   Calling a function with a [[Variadic function|variable number of arguments]]
:*   Calling a function with [[Named parameters|named arguments]]
:*   Using a function in statement context
:*   Using a function in [[First-class functions|first-class context]] within an expression
:*   Obtaining the return value of a function
:*   Distinguishing built-in functions and user-defined functions
:*   Distinguishing subroutines and functions
;*   Stating whether arguments are [[:Category:Parameter passing|passed]] by value or by reference
;*   Is partial application possible and how

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This task is ''not'' about [[Function definition|defining functions]].
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