example.py

print_grid(
  columns=('Function', 'Occurences', 'Sender'),
  values=[(x['function'], 1337, x['sender']) for x in messages if 'function' in x]
)

foo.py

def print_grid(columns, values, spacing=1, separator='|'):
    header_str = ''
    format_str = ''
    for index in range(len(columns)):
        longest = max([len(str(row[index])) for row in [columns] + values])
        header_str += '{:' + str(longest) + '}'
        format_str += '{:' + str(longest) + '}'
        if index != len(columns) - 1:
            header_str += ' ' * spacing
            format_str += ' ' * spacing
            if separator:
                header_str += ' ' * (len(separator) + spacing)
                format_str += separator + ' ' * spacing
    print header_str.format(*columns)
    for row in values:
        print format_str.format(*row)

print_grid(
    columns=('Function', 'Occurences', 'Sender'), 
    values=[
        ('hey', 'world', 'foobar'),
        ('this is', 'a test', 'my man!'),
        ('roar', 'grr', 'zzzz'),
    ]
)

"""
Function   Occurences   Sender 
hey      | world      | foobar 
this is  | a test     | my man!
roar     | grr        | zzzz   
"""

simple.py

def print_grid(columns, values):
    # pop columns on top of values, since we want to print them as well
    values = [columns] + values

    # calculate the format string for printing a row
    row_format = ''
    for index in range(len(columns)):
        longest = max([len(str(row[index])) for row in values])
        row_format += '{:' + str(longest) + '} '

    # print the row!
    for row in values:
        print row_format.format(*row)