human
Solve the following python programming problem given the following code:
def ensure_dtype(func, argname, arg) : 
    "
    Argument preprocessor that converts the input into a numpy dtype.

    Usage
    -----
    >>> import numpy as np
    >>> from zipline.utils.preprocess import preprocess
    >>> @preprocess(dtype=ensure_dtype)
    ... def foo(dtype):
    ...     return dtype
    ...
    >>> foo(float)
    dtype('float64')
    " 
    try : 
        return dtype (arg) 
except TypeError : 
        raise TypeError ("{func}() couldn't convert argument {argname}={arg!r} to a numpy dtype.".format (func = _qualified_name (func), argname = argname, arg = func)) 

    
    

    Fix the buggy line: raise TypeError ("{func}() couldn't convert argument {argname}={arg!r} to a numpy dtype.".format (func = _qualified_name (func), argname = argname, arg = func))
assistant
#Here is Python program to fix the buggy line: raise TypeError ("{func}() couldn't convert argument {argname}={arg!r} to a numpy dtype.

raise TypeError ("{func}() couldn't convert argument {argname}={arg!r} to a numpy dtype.".format (func = _qualified_name (func), argname = argname, arg = arg))