input: Write a python function to format a given text with specified font, size, and color.
  assert format_text('Hello World', font="Arial", size='20px', color='#FF5733') == "<span style='font-family: Arial font-size: 20px color: #FF5733'>Hello World</span>"
  assert format_text('Python Programming', size='18px', color='#00FF00') == "<span style='font-family: Times New Roman font-size: 18px color: #00FF00'>Python Programming</span>"
  assert format_text('Sample Text') == "<span style='font-family: Times New Roman font-size: 14px color: #000000'>Sample 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>"