input: Write a function to compute the edit distance between two strings using dynamic programming. The function should return the minimum number of operations (insertion, deletion, substitution) required to transform one string into the other. 
  
  assert edit_distance("kitten", "sitting") == 3
  assert edit_distance("flaw", "lawn") == 2
  assert edit_distance("intention", "execution") == 5
  assert edit_distance("", "abc") == 3
  assert edit_distance("abc", "") == 3
output: def edit_distance(str1, str2):
      m, n = len(str1), len(str2)
      dp = [[0] * (n + 1) for _ in range(m + 1)]
      
      for i in range(m + 1):
          for j in range(n + 1):
              if i == 0:
                  dp[i][j] = j
              elif j == 0:
                  dp[i][j] = i
              elif str1[i-1] == str2[j-1]:
                  dp[i][j] = dp[i-1][j-1]
              else:
                  dp[i][j] = 1 + min(dp[i-1][j], dp[i][j-1], dp[i-1][j-1])
      
      return dp[m][n]