input: Write a function to format a given piece of text with different options for font-style, size, and color. The function should return a formatted HTML string.
  assert format_text('Lorem ipsum dolor sit amet, consectetur adipiscing elit. Integer ut lectus vel nisi consequat bibendum ac a erat. Aliquam non velit sit amet arcu placerat vulputate a ut nibh.') == "<span style='font-family: Times New Roman font-size: 14px color: #000000'>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Integer ut lectus vel nisi consequat bibendum ac a erat. Aliquam non velit sit amet arcu placerat vulputate a ut nibh.</span>"
  assert format_text('Hello World', font='Arial', size='20px', color='#FF0000') == "<span style='font-family: Arial font-size: 20px color: #FF0000'>Hello World</span>"
  assert format_text('Testing', font='Helvetica', size='12px', color='#00FF00') == "<span style='font-family: Helvetica font-size: 12px color: #00FF00'>Testing</span>"
  assert format_text('Final Test', font='Verdana', size='18px', color='#0000FF') == "<span style='font-family: Verdana font-size: 18px color: #0000FF'>Final Test</span>"
  assert format_text('Empty Text') == "<span style='font-family: Times New Roman font-size: 14px color: #000000'>Empty Text</span>"
output: def format_text(text, font='Times New Roman', size='14px', color='#000000'):
      return f"<span style='font-family: {font} font-size: {size} color: {color}'>{text}</span>"