proc `+`(p: GgPlot; d: VegaDraw) {....raises: [Exception, ValueError, KeyError,
    FormulaMismatchError, AestheticError, IOError, OSError, JsonParsingError], tags: [
    RootEffect, ReadIOEffect, WriteIOEffect, ReadEnvEffect, WriteDirEffect].}

proc ggvegaCreate(p: GgPlot; vegaDraw: VegaDraw): JsonNode {....raises: [Exception,
    ValueError, KeyError, FormulaMismatchError, AestheticError, IOError,
    OSError, JsonParsingError], tags: [RootEffect, ReadIOEffect, WriteIOEffect].}

proc showVega(data: JsonNode; fname: string) {.
    ...raises: [ValueError, OSError, IOError, Exception], tags: [ReadEnvEffect,
    ReadIOEffect, WriteIOEffect, RootEffect, WriteDirEffect].}

proc toVegaLite(p: GgPlot; filledScales: FilledScales; theme: Theme;
                width, height: float): JsonNode {....raises: [IOError, OSError,
    JsonParsingError, ValueError, Exception, KeyError, FormulaMismatchError],
    tags: [ReadIOEffect, WriteIOEffect, RootEffect].}