input: Write a function to compute the edit distance between two given strings in Python. The function should return the minimum number of operations (insertions, deletions, or substitutions) required to transform the first string into the second string.
  assert editDistance("kitten", "sitting", len("kitten"), len("sitting"))==3
  assert editDistance("intention", "execution", len("intention"), len("execution"))==5
  assert editDistance("cat", "rat", len("cat"), len("rat"))==1
  assert editDistance("apple", "apples", len("apple"), len("apples"))==1
  assert editDistance("abcd", "efgh", len("abcd"), len("efgh"))==4
output: def editDistance(str1, str2, m, n):
      dp = [[0 for x in range(n + 1)] for x 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][j-1], dp[i-1][j], dp[i-1][j-1])
      
      return dp[m][n]