Printing { and } with new format syntax

I need to add '{' and/or '}' in a string where I use the format function to format the开发者_运维技巧 string. For example: I want my string to be "{3}", but this:

"\{{}\}".format(3)

gives me the error:

ValueError: Single '}' encountered in format string

Does anyone know how use '{' and '}' in string formatting?

Thanks, Jeremy

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Simply duplicate the braces:

>>> "{{{0}}}".format(3)
'{3}'

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print "{{{0}}}".format(3)
'{3}'

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If you need unmatched brackets you could use something like:

>>> " {c}{x}{o}{o}".format(o='{',c='}', x=3)
' }3{{' 

The doubling works for unmatched braces as well:

>>> "}} {} {{ {{".format(3)
'} 3  { {'