protected boolean consumeOptional(char character) {
            skipSpace();

            if (position >= string.length())
                return false;
            if ( string.charAt(position) != character)
                return false;

            position++;
            return true;
        }
Derives the tensor type from the first address string in the given tensor string
vespajlib/src/main/java/com/yahoo/tensor/TensorParser.java