input: Write a function to format a given piece of text (input) with different options for font-style, size, and color. If no options are provided, use default values for font ('Times New Roman'), size ('14px'), and color ('#000000'). If the input text is empty, return an empty 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='16px', color='#FF0000')=='<span style=\'font-family: Arial font-size: 16px color: #FF0000\'>Hello World</span>'
  assert format_text('', font='Courier', size='12px', color='#00FF00')==''
  assert format_text('Test', size='20px')=='<span style=\'font-family: Times New Roman font-size: 20px color: #000000\'>Test</span>'
  assert format_text('Sample Text', color='#0000FF')=='<span style=\'font-family: Times New Roman font-size: 14px color: #0000FF\'>Sample Text</span>'
output: def format_text(input, font='Times New Roman', size='14px', color='#000000'):
      if not input:
          return ''
      return f"<span style='font-family: {font} font-size: {size} color: {color}'>{input}</span>"