input: 
  class Matrix:
      def __init__(self, m, n, lst):
          self.m = m
          self.n = n
          self.mat = []
  
          c = 0
          for i in range(self.m):
              a = []
              for j in range(self.n):
                  a.append(lst[c])
                  c += 1
              self.mat.append(a)
  
      def __str__(self):
          output = ""
          for i in self.mat:
              for j in i:
                  output += str(j) + " "
              output += '\n'
          return output
  
      def add(self, mat2):
          for i in range(self.m):
              for j in range(self.n):
                  self.mat[i][j] += mat2.mat[i][j]
  
      def sub(self, mat2):
          for i in range(self.m):
              for j in range(self.n):
                  self.mat[i][j] -= mat2.mat[i][j]
  
      def mul(self, mat2):
          result = []
          for i in range(self.m):
              a = []
              for j in range(mat2.n):
                  s = 0
                  for k in range(self.n):
                      s += self.mat[i][k] * mat2.mat[k][j]
                  a.append(s)
              result.append(a)
          self.mat = result
          self.m = len(result)
          self.n = len(result[0])
  
      def transpose(self):
          result = [[self.mat[j][i] for j in range(len(self.mat))] for i in range(len(self.mat[0]))]
          self.mat = result
          self.m = len(result)
          self.n = len(result[0])
  
  # Testing the Matrix class
  matrix1 = Matrix(2, 2, [1, 2, 3, 4])
  matrix2 = Matrix(2, 2, [5, 6, 7, 8])
  matrix1.add(matrix2)
  print(matrix1)  # Output: 6 8 \n 10 12 \n
  matrix1 = Matrix(2, 2, [1, 2, 3, 4])
  matrix1.sub(matrix2)
  print(matrix1)  # Output: -4 -4 \n -4 -4 \n
  matrix1 = Matrix(2, 3, [1, 2, 3, 4, 5, 6])
  matrix2 = Matrix(3, 2, [7, 8, 9, 10, 11, 12])
  matrix1.mul(matrix2)
  print(matrix1)  # Output: 58 64 \n 139 154 \n
  matrix1 = Matrix(2, 2, [1, 2, 3, 4])
  matrix1.transpose()
  print(matrix1)  # Output: 1 3 \n 2 4 \n
  
output:     
      def scalar_mul(self, scalar):
          for i in range(self.m):
              for j in range(self.n):
                  self.mat[i][j] *= scalar
  
      def get_element(self, i, j):
          return self.mat[i][j]
  
      def set_element(self, i, j, value):
          self.mat[i][j] = value
  
      def is_square(self):
          return self.m == self.n
  
      def is_symmetric(self):
          if not self.is_square():
              return False
          for i in range(self.m):
              for j in range(i + 1, self.n):
                  if self.mat[i][j] != self.mat[j][i]:
                      return False
          return True
  
  # Additional testing for new methods
  matrix1 = Matrix(2, 2, [1, 2, 2, 1])
  matrix1.scalar_mul(2)
  print(matrix1)  # Output: 2 4 \n 4 2 \n
  print(matrix1.get_element(0, 1))  # Output: 4
  matrix1.set_element(0, 1, 3)
  print(matrix1)  # Output: 2 3 \n 4 2 \n
  print(matrix1.is_square())  # Output: True
  print(matrix1.is_symmetric())  # Output: False
  matrix1 = Matrix(2, 2, [1, 2, 2, 1])
  print(matrix1.is_symmetric())  # Output: True
  