title: - add player(self, Player Name, Player Number, Player Salary per week, Signing Date, contract duration in years, number of matches played)
body: <p>add player(self, Player Name, Player Number, Player Salary per
  week, Signing Date, contract duration in years, number of
  matches played)
  a- first search if the player number is already exists or not.
  b- If the player number is already exist in the team =&gt; print
  (“change the player number”)
  c- Else =&gt; create a Player object with the given data
  d- Add this player object to the Players List.
  e- Increase the Number of Players by +1</p>