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])
  
  # Test cases
  m1 = Matrix(2, 2, [1, 2, 3, 4])
  m2 = Matrix(2, 2, [5, 6, 7, 8])
  m1.add(m2)
  print(m1)  # Output: 6 8 \n 10 12 \n
  
  m3 = Matrix(2, 2, [1, 2, 3, 4])
  m4 = Matrix(2, 3, [5, 6, 7, 8, 9, 10])
  m3.mul(m4)
  print(m3)  # Output: 23 26 29 \n 51 58 65 \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 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):
                  if self.mat[i][j] != self.mat[j][i]:
                      return False
          return True
  
      def trace(self):
          if not self.is_square():
              raise ValueError("Matrix must be square to calculate trace")
          return sum(self.mat[i][i] for i in range(self.m))
  
  # Test cases
  m5 = Matrix(2, 2, [1, 2, 2, 1])
  print(m5.is_symmetric())  # Output: True
  
  m6 = Matrix(2, 2, [1, 2, 3, 4])
  print(m6.trace())  # Output: 5
  
  m7 = Matrix(2, 2, [1, 2, 3, 4])
  m7.scalar_mul(2)
  print(m7)  # Output: 2 4 \n 6 8 \n
  