Please solve the programming task below using a self-contained code snippet in a markdown code block.

A cell (r, c) of an excel sheet is represented as a string "<col><row>" where:

<col> denotes the column number c of the cell. It is represented by alphabetical letters.

	
For example, the 1st column is denoted by 'A', the 2nd by 'B', the 3rd by 'C', and so on.


<row> is the row number r of the cell. The rth row is represented by the integer r.

You are given a string s in the format "<col1><row1>:<col2><row2>", where <col1> represents the column c1, <row1> represents the row r1, <col2> represents the column c2, and <row2> represents the row r2, such that r1 <= r2 and c1 <= c2.
Return the list of cells (x, y) such that r1 <= x <= r2 and c1 <= y <= c2. The cells should be represented as strings in the format mentioned above and be sorted in non-decreasing order first by columns and then by rows.
 
Please complete the following python code precisely:
```python
class Solution:
    def cellsInRange(self, s: str) -> List[str]:
```