_contains

Produces true if the received List contains the specified value -- Function
Anything -> _contains (v, all) -> TrueOrFalse Type
Receives
A List (or Set) of any sort
v
A single value that might be in the List. This should be Required; if not, the first element will be used.
all (optional)
If you set this to true, all of the values must be present; otherwise, it will return true if any are present.
Produces
True if v is found in the List; False otherwise
See _isContainedIn for the inverse of this function.