To find the largest among three numbers in Python, you can use the following code:

```				```
# define a function to find the largest number
def find_largest(num1, num2, num3):
# check if num1 is greater than num2 and num3
if num1 > num2 and num1 > num3:
return num1
# check if num2 is greater than num1 and num3
elif num2 > num1 and num2 > num3:
return num2
# if the above conditions are not met, return num3
else:
return num3

# take input from the user
num1 = int(input("Enter the first number: "))
num2 = int(input("Enter the second number: "))
num3 = int(input("Enter the third number: "))

# call the function and print the result
largest = find_largest(num1, num2, num3)
print("The largest number is", largest)

```
```

This code first defines a function `find_largest()` that takes three numbers as arguments and returns the largest number among them. The function checks if each number is greater than the other two numbers, and returns the number if it is. If none of the numbers is greater than the other two, it returns the last number.

After defining the function, the code takes three numbers as input from the user using the `input()` function and stores them in variables `num1`, `num2`, and `num3`. It then calls the `find_largest()` function and passes these three numbers as arguments. The returned value (the largest number) is stored in the variable `largest` and is printed using the `print()` function.