input: Write a function to create an HTML formatted string of a given piece of text with specified font-style, size, and color. If no font-style, size, or color is provided, use default values of "Times New Roman", "14px", and "#000000" respectively. The function should return the formatted string.
  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('Lorem ipsum dolor sit amet, consectetur adipiscing elit.', 'Arial', '12px', '#FF0000') == "<span style='font-family: Arial font-size: 12px color: #FF0000'>Lorem ipsum dolor sit amet, consectetur adipiscing elit.</span>"
  assert format_text('') == "<span style='font-family: Times New Roman font-size: 14px color: #000000'></span>"
  assert format_text('Lorem ipsum dolor sit amet, consectetur adipiscing elit.', size='20px') == "<span style='font-family: Times New Roman font-size: 20px color: #000000'>Lorem ipsum dolor sit amet, consectetur adipiscing elit.</span>"
  assert format_text('Lorem ipsum dolor sit amet, consectetur adipiscing elit.', color='#FFFFFF') == "<span style='font-family: Times New Roman font-size: 14px color: #FFFFFF'>Lorem ipsum dolor sit amet, consectetur adipiscing elit.</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)