public boolean containsValue(Object value) {
        return indexOfValue(value) >= 0;
    }
Check whether a value exists in the array.  This requires a linear search
through the entire array.

@param value The value to search for.
@return Returns true if the value exists, else false.
core/src/main/java/com/bluelinelabs/logansquare/util/SimpleArrayMap.java