> For the complete documentation index, see [llms.txt](https://max-daunarovich.gitbook.io/flow-network/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://max-daunarovich.gitbook.io/flow-network/introduction/functions/function-calls.md).

# Function Calls

Functions can be called (invoked). Function calls need to provide exactly as many argument values as the function has parameters.

```
fun double(_ x: Int): Int {
    return x * 2
}

// Valid: the correct amount of arguments is provided.
//
double(2)  // is `4`

// Invalid: too many arguments are provided.
//
double(2, 3)

// Invalid: too few arguments are provided.
//
double()
```