input: Write a python function to compute the edit distance between two strings.
  assert edit_distance("kitten", "sitting") == 3
  assert edit_distance("flaw", "lawn") == 2
  assert edit_distance("intention", "execution") == 5
  assert edit_distance("", "") == 0
  assert edit_distance("abc", "def") == 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]