O(n) The elemIndices function extends elemIndex,
by returning the indices of all elements equal to the query element,
in ascending order. This implementation uses memchr(3).
O(n) The elemIndices function extends elemIndex,
by returning the indices of all elements equal to the query element,
in ascending order. This implementation uses memchr(3).
Return indices of all elements, equal to a given.
This function isn't productive (e. g., head .
elemIndicesf won't terminate), if no elements of the
input list are equal the given one.