sig
type ('a, 'b) df_analysis_context
val build_df_analysis_context :
unit -> ('a, 'b) Df_analysis_context.df_analysis_context
val add_var_dfgraph :
('a, 'b) Df_analysis_context.df_analysis_context ->
Xquery_common_ast.cvname ->
('a, 'b) Df_struct.dfgraph ->
('a, 'b) Df_analysis_context.df_analysis_context
val get_var_dfgraph :
('a, 'b) Df_analysis_context.df_analysis_context ->
Xquery_common_ast.cvname -> ('a, 'b) Df_struct.dfgraph
end