'Replace the value of a column at a given position.
Parameters
row : int
Row number to modify
col_name : str
Name of the Column to modify
val : col.info.dtype
Value to insert at specified row of col'

def replace(self, row, col_name, val):

    self.remove_row(row, reorder=False)
    key = [c[row] for c in self.columns]
    key[self.col_position(col_name)] = val
    self.data.add(tuple(key), row)
