what is the syntax error in this code in python? -

i'm new in programming , in python , watching lecture , wanted create simple functions lecturer in video , design 3 functions , addition , mean , mean_addition show below , addition add 2 numbers , mean function calculate mean of 2 numbers mean_addition adds mean , addition of 2 numbers

i writed code , run program had told me there syntax error , checked on , on again can't decide wrong

the code of simple programme :

def addition(float1,float2):      '''(float,float)-> float  return addition of float1 , float2 .  >>> addition(2,3) 5.0 >>>addition(4,6) 10.0 '''      return float1+float2   def mean(x , y ):     ''' (number,number)-> float return mean of 2 numbers , x , y . >>> mean(2,4)  3.0 >>> mean(9,2) 5.5  '''     return  addition(x,y)/ 2    def mean_addition(t,s): ''' (float,float)->float return mean of 2 numbers plus addition of 2 numbers >>> mean_addition(1,2) 4.5 >>> mean_addition(4,5) 13.5 '''     return addition(t,s) + mean(t,s) 

one thing want mention error in third function mean_addition because when deleted part worked !

the problem , when choose run modulo says "expected indented block"

so syntax error have made ?

thanks.

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note : explore question in future , syntax error made ( learned answer ) wrote

def mean_addition(t,s): ''' (float,float)->float 

but shouldn't put " ''' " under "def" , should make space under "def" right code

def mean_addition(t,s):     ''' (float,float)->float 

def addition(float1,float2):      '''(float,float)-> float  return addition of float1 , float2 .  >>> addition(2,3) 5.0 >>>addition(4,6) 10.0 '''      return float1+float2   def mean(x , y ):     ''' (number,number)-> float return mean of 2 numbers , x , y . >>> mean(2,4)  3.0 >>> mean(9,2) 5.5  '''     return  addition(x,y)/ 2    def mean_addition(t,s):     ''' <----- error here (float,float)->float return mean of 2 numbers plus addition of 2 numbers >>> mean_addition(1,2) 4.5 >>> mean_addition(4,5) 13.5 '''     return addition(t,s) + mean(t,s)