input: Write a function to format a given piece of text with options for font-style, size, and color. The function should return the formatted text as a string with the specified styles applied. If no styles are provided, default values should be used. Default font is "Times New Roman", default size is '14px', and default color is '#000000'.
  
  def format_text(text, font="Times New Roman", size='14px', color='#000000'):
    return "<span style='font-family: {}; font-size: {}; color: {};'>{}</span>".format(font, size, color, text)
  
  assert format_text('Lorem ipsum dolor sit amet, consectetur adipiscing elit.') == "<span style='font-family: Times New Roman; font-size: 14px; color: #000000;'>Lorem ipsum dolor sit amet, consectetur adipiscing elit.</span>"
  assert format_text('Aliquam non velit.', font="Arial", size='12px', color='#FF0000') == "<span style='font-family: Arial; font-size: 12px; color: #FF0000;'>Aliquam non velit.</span>"
  assert format_text('Integer ut lectus vel nisi consequat bibendum ac a erat.') == "<span style='font-family: Times New Roman; font-size: 14px; color: #000000;'>Integer ut lectus vel nisi consequat bibendum ac a erat.</span>"
  assert format_text('Ut nibh placerat vulputate.', size='16px') == "<span style='font-family: Times New Roman; font-size: 16px; color: #000000;'>Ut nibh placerat vulputate.</span>"
output: def format_text(text, font="Times New Roman", size='14px', color='#000000'):
    return "<span style='font-family: {}; font-size: {}; color: {};'>{}</span>".format(font, size, color, text)