SyntaxError:keyword can't be an expression

def build_profile(first_name,last_name,*messages):

profile={}

profile['first_name']=first_name.title()

profile['last_name']=last_name.title()

for a,b in messages.items():

profile[a]=b

return profile

user_profile=build_profile('zuozheng','li',

'old'='29',

'tall'='175',)

print(user_profile)