def create(row_num, col_num, val = None):
	"""
	:param row_num: the number of rows
	:type row_num: int
	:param col_num: the number of columns
	:type col_num: int
	:param val: the default value to fill the matrix
	:type val: any (None by default)
	:return: matrix of rows_num x col_num
	:rtype: matrix
	"""
	matrix = []
	for i in range(col_num):
		col = [val] * row_num
		matrix.append(col)
	return matrix