function <function_name> with <param1>, <param2>, ...:
    <function_body>
    return <value>

function greet with name:
    set message to f"Hello, {name}!"
    return message

set greeting to call greet with "Alice"
print greeting  # Prints: Hello, Alice!

function add with a, b:
    return a plus b

set result to call add with 5, 3
print result  # Prints: 8

function calculate_total with price, quantity, tax_rate:
    set subtotal to price times quantity
    set tax to subtotal times tax_rate
    return subtotal plus tax

set total to call calculate_total with 10.0, 3, 0.08
print total

set global_var to "global"

function test_scope:
    set local_var to "local"
    print global_var  # Can access global variables
    print local_var   # Can access local variables

call test_scope
print global_var  # OK: global variable
print local_var   # Error: local_var is not defined

function fibonacci with n:
    if n is less than 2:
        return n
    
    set a to 0
    set b to 1
    
    for i in range 2 to n:
        set temp to b
        let b to a plus b
        let a to temp
    
    return b

print call fibonacci with 10  # Prints: 55

function factorial with n:
    if n is less than or equal 1:
        return 1
    
    let result to 1
    for i in range 2 to n:
        let result to result times i
    
    return result

print call factorial with 5  # Prints: 120

function get_grade with score:
    if score is greater than 90:
        return "A"
    else if score is greater than 80:
        return "B"
    else if score is greater than 70:
        return "C"
    else:
        return "F"

print call get_grade with 85  # Prints: B