Checks if the given container type has the given value in it. This function behave slightly differently based on whether the first argument is an object, a list, or a string. This function is case-sensitive.
For objects, checks if the object has a key with the given name. For example,
contains(file, "ctime") = truecontains(file, "day") = true (if file has a date in its title, false otherwise)
For lists, checks if any of the array elements equals the given value. For example,