constructs a float number from an integer literal, a float literal or a string literal
print(float(1)) # prints 1.0
print(float(2.8)) # prints 2.8
print(float("3")) # prints 3.0
print(float("4.2")) # prints 4.2
str()
constructs a string from a wide variety of data types, including strings, integer literals and float literals
print(str("s1")) # prints 's1'
print(str(2)) # prints '2'
print(str(3.0)) # prints '3.0'
#convert from int to float:
x = float(1)
#convert from float to int:
y = int(2.8)
#convert from int to complex:
z = complex(x)
print(x)#prints 1.0
print(y)#prints 2
print(z)#prints (1+0j)