removeRange method
Removes the objects in the range start inclusive to end exclusive.
The provide range, given by start and end, must be valid.
A range from start to end is valid if 0 <= start <= end <= len, where
len is this list's length. The range starts at start and has length
end - start. An empty range (with end == start) is valid.
Throws an UnsupportedError if this is a fixed-length list. In that case the list is not modified.
Implementation
void removeRange(int start, int end) {
throw new UnsupportedError("Cannot removeRange on immutable List.");
}