List
LPOS
Returns the index of matching elements inside a list.
Arguments
The key of the list.
The element to match.
opts
The rank of the element to match. If specified, the element at the given rank is matched instead of the first element.
The maximum number of elements to match. If specified, an array of elements is returned instead of a single element.
Limit the number of comparisons to perform.
Response
The index of the matching element or an array of indexes if opts.count is
specified.