Notes:
Some Unicode string functions will not behave correctly because ICU data file
    icudt54l.dat cannot be found at directory:
    "D:\STATA学习资料\Stata14\utilities"
      1.  Unicode is supported; see help unicode_advice.
      2.  More than 2 billion observations are allowed; see help obs_advice.
      3.  Maximum number of variables is set to 5000; see help set_maxvar.

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