docs: def remove(self):
          """Remove duplicate lines from text files"""
          num, sp, newfile = 0, "", []
          if os.path.isfile(self.filename):
              with open(self.filename, "r") as r:
                  oldfile = r.read().splitlines()
                  for line in oldfile:
                      if self.number:
                          num += 1
                          sp = ": "
                      if self.case_ins:
                          line = line.lower()
                      if self.ignore_blank and not line:
                          newfile.append(line)
                      elif line not in newfile:
                          newfile.append(line)
                      else:
                          if (self.args[0] in self.options[4:5] or
                                  self.args[0] in self.options[6:7]):
                              if num == 0:
                                  num = str()
                              print("{0}{1}{2}".format(num, sp, line))
              if self.args[0] not in self.options[6:7]:
                  with open(self.filename, "w") as w:
                      for line in newfile:
                          w.write(line + "\n")
          else:
              self.not_access()