Unexpected Indent error in Python [duplicate]

This question already has answers here: I'm getting an IndentationError. How do I fix it? (5 answers) Closed 3 years ago.

I have a simple piece of code that I'm not understanding where my error is coming from. The parser is barking at me with an Unexpected Indent on line 5 (the if statement). Does anyone see the problem here? I don't.

def gen_fibs():
    a, b = 0, 1
    while True:
        a, b = b, a + b
        if len(str(a)) == 1000:
          开发者_运维百科  return a

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If you just copy+pasted your code, then you used a tab on the line with the if statement. Python interprets a tab as 8 spaces and not 4. Don't ever use tabs with python¹ :)

^{1 Or at least don't ever use tabs and spaces mixed. It's highly advisable to use 4 spaces for consistency with the rest of the python universe.}

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You're mixing tabs and spaces. Tabs are always considered the same as 8 spaces for the purposes of indenting. Run the script with python -tt to verify.

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Check if you aren't mixing tabs with spaces or something, because your code pasted verbatim doesn't produce any errors.

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The line with a, b = b, a + b is indented with 8 spaces, and the if line is indented with 4 spaces and a tab. Configure your editor to never ever insert tabs ever.

(Python considers a tab to be 8 spaces, but it's easier just not to use them)

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Check whether your whitespace in front of every line is correctly typed. You may have typed tabs instead of spaces - try deleting all the space and change it so you use only tabs or only spaces.