def matrixvector_multiply(a, x):
	"""takes a matrix and a vector represented as a list of list and multiplies them"""

	if len(a[0]) == len(x):
		product = []

		for i in range(len(a)):
			product.append(0)
			for j in range(len(x)):
				product[i] += a[i][j]*x[j]
		return product 
	else:
		return """ Matrix Vector Multiplication cannot be carried out because the number of rows of the matrix 'a' is 
					not equal to the number of columns of the vector 'x' """