input: Write a function that takes a piece of text and formats it with specified font-style, font-size, and color options. If the function is provided with no additional options, it should use default values for font-style ("Times New Roman"), font-size ("14px"), and color ("#000000"). If the text is formatted correctly, return the formatted HTML string; if not, return an error message.
  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('Lorem ipsum dolor sit amet, consectetur adipiscing elit.', "Arial", "16px", "#FF0000")=='<span style=\'font-family: Arial\' font-size: 16px color: #FF0000\'>Lorem ipsum dolor sit amet, consectetur adipiscing elit.</span>'
  assert format_text('Hello', size="20px")=='<span style=\'font-family: Times New Roman\' font-size: 20px color: #000000\'>Hello</span>'
  assert format_text('World', color="#00FF00")=='<span style=\'font-family: Times New Roman\' font-size: 14px color: #00FF00\'>World</span>'
  assert format_text('')=='<span style=\'font-family: Times New Roman\' font-size: 14px color: #000000\'></span>'
output: def format_text(text, font_style="Times New Roman", size="14px", color="#000000"):
      return f'<span style=\'font-family: {font_style}\' font-size: {size} color: {color}\'>{text}</span>'