I am trying to implement a method GLM’s linear model. Unfortunately, I can’t specify this type in the function.

```
using GLM, RDatasets
iris = dataset("datasets", "iris")
fit = lm(@formula(SepalLength ~ PetalWidth), iris)
function print_r2(fit::LinearModel)
R2 = r2(fit)
R2_Adj = adjr2(fit)
println("The model's explanatory power (R2) is of $(round(R2, 2)) (Adj. R2 = $(round(R2_Adj, 2))).")
end
print_r2(fit)
```

```
MethodError: no method matching print_r2(::StatsModels.DataFrameRegressionModel{GLM.LinearModel{GLM.LmResp{Array{Float64,1}},GLM.DensePredChol{Float64,Base.LinAlg.Cholesky{Float64,Array{Float64,2}}}},Array{Float64,2}})
Closest candidates are:
print_r2(::GLM.LinearModel) at In[7]:9
```

What is wrong with it? Should I specify the whole big type (StatsModels.DataFrame…) ?