matrix.py

def multiply(m1, m2):
    x1 = len(m1[0])
    y1 = len(m1)
    x2 = len(m2[0])
    y2 = len(m2)

    if(x1!=y2):
        return("Error. Bad Matrix")

    x3 = x2
    y3 = y1
    c = x1

    Result = [[0 for x in range(x3)] for y in range(y3)]
    for x in range(x3):
        for y in range(y3):
            answer = 0
            for i in range(c):
                product = m1[x][i] * m2[i][y]
                answer+=product
            Result[x][y] = answer
    
    return(Result)

Matrix1 = [[1, 2], [3, 4]]
Matrix2 = [[2, 0], [1, 2]]

print(multiply(Matrix1, Matrix2))

Matrix1 = [[1, 2, 3], [4, 5, 6]]
Matrix2 = [[7, 8], [9, 10], [11, 12]]

print(multiply(Matrix1, Matrix2))