input: Write a function to generate and display a Fibonacci sequence of the first n numbers. The function should return the nth Fibonacci number. If n is 1 it should return 0, if n is 2 it should return 1, otherwise it should return the sum of the two preceding numbers in the sequence.
  def Fibonacci(n):
      if n==1:
          return 0
      elif n==2:
          return 1
      else:
          return Fibonacci(n-1)+Fibonacci(n-2)
  assert Fibonacci(1)==0
  assert Fibonacci(2)==1
  assert Fibonacci(3)==1
  assert Fibonacci(4)==2
  assert Fibonacci(5)==3
  assert Fibonacci(6)==5
  assert Fibonacci(7)==8
  assert Fibonacci(8)==13
  assert Fibonacci(9)==21
  assert Fibonacci(10)==34
output: def Fibonacci(n):
      if n==1:
          return 0
      elif n==2:
          return 1
      else:
          return Fibonacci(n-1)+Fibonacci(n-2)