<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def ensure_int64_or_float64(arr, copy=False):
 """ Ensure that an dtype array of some integer dtype has an int64 dtype if possible If it's not possible, potentially because of overflow, convert the array to float64 instead. Parameters arr : array-like The array whose data type we want to enforce. copy: boolean Whether to copy the original array or reuse it in place, if possible. Returns ------- out_arr : The input array cast as int64 if possible without overflow. Otherwise the input array cast to float64. """

    try:
        return arr.astype('int64', copy=copy, casting='safe')
    except TypeError:
        return arr.astype('float64', copy=copy)