test = 'I am {name},age{a}'
#v = test.format(name = 'alex',a =19)
v = test.format(**{"name" : 'alex',"a":19})
print(v)


_____________________________
I am alex,age19

test = 'I am {0},age{0}'
# v = test.format(name = 'alex',a =19)
#v = test.format(**{"name" : 'alex',"a":19})
v = test.format('alex',19)

print(v)

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I am alex,age 19