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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def validate(self, grid):
 """ Using the MagIC data model, generate validation errors on a MagicGrid. Parameters grid : dialogs.magic_grid3.MagicGrid The MagicGrid to be validated Returns --------- warnings: dict Empty dict if no warnings, otherwise a dict with format {name of problem: [problem_columns]} """

        grid_name = str(grid.GetName())
        dmodel = self.contribution.dmodel
        reqd_headers = dmodel.get_reqd_headers(grid_name)
        df = self.contribution.tables[grid_name].df
        df = df.replace('', np.nan) # python does not view empty strings as null
        if df.empty:
            return {}
        col_names = set(df.columns)
        missing_headers = set(reqd_headers) - col_names
        present_headers = set(reqd_headers) - set(missing_headers)
        non_null_headers = df.dropna(how='all', axis='columns').columns
        null_reqd_headers = present_headers - set(non_null_headers)
        if any(missing_headers) or any (null_reqd_headers):
            warnings = {'missing required column(s)': sorted(missing_headers),
                        'no data in required column(s)': sorted(null_reqd_headers)}
        else:
            warnings = {}
        return warnings