def sum_positive(some_list):
    '''Return a sum of all the positive values of some_list.'''
    running_sum = 0
    for num in some_list:
        if num > 0:
            running_sum += num
    return running_sum


def list_min(some_list):
    '''Return the minimum value of some_list without using the built-in min.'''
    min_so_far = some_list[0]
    for elem in some_list:
        if elem < min_so_far:
            min_so_far = elem
    return min_so_far


def extract_uppercase(string):
    '''Returns a new string consisting of only the uppercase characters
    of string.'''
    upper_so_far = ''
    for char in string:
        if char.isupper():
            upper_so_far += char
    return upper_so_far


def print_students(student_list):
    '''Print each student 2-tuple as name and class year.'''
    for (name, year) in student_list:
        print('Name is ' + name + ', year is ' + str(year))


def print_1_to_100():
    '''Print all the numbers from 1 to 100'''
    for num in range(1, 101):
        print(num)
        

def print_list(some_list):
    '''Prints all elements of some_list using a for each loop.'''
    for element in some_list:
        print(element)


def print_list_range(some_list):
    '''Prints all elements of some_list using a range loop.'''
    for i in range(0, len(some_list)):
        print(some_list[i])
        
        
def print_list_indices(some_list):
    '''Print each element and its index of some_list.'''
    # Range loop version
    for i in range(0, len(some_list)):
        print('Element {0} is {1}'.format(i, some_list[i]))
    
    # Equivalent enumerate version
    for (index, element) in enumerate(some_list):
        print('Element {0} is {1}'.format(index, element))
        

def scale_grades(grades_list):
    '''Given a list of numeric grades, scale the grades in the list
    up by 10%. This *modifies* the given list.'''
    for i in range(0, len(grades_list)):
        grades_list[i] *= 1.1