Apply functions over file array margins (extended)

## Usage

```
apply(X, MARGIN, FUN, ..., simplify = TRUE)
# S4 method for FileArray
apply(X, MARGIN, FUN, ..., simplify = TRUE)
# S4 method for FileArrayProxy
apply(X, MARGIN, FUN, ..., simplify = TRUE)
```

## Arguments

- X
a file array

- MARGIN
scalar giving the subscripts which the function will be applied over. Current implementation only allows margin size to be one

- FUN
the function to be applied

- ...
optional arguments to

`FUN`

- simplify
a logical indicating whether results should be simplified if possible

## Value

See Section 'Value' in `apply`

;