# Understanding the notation (arr = \[1.2\], arr2=\[5, 7\])

**URL:** <https://discourse.julialang.org/t/understanding-the-notation-arr-1-2-arr2-5-7/45363>\
**Category:** New to Julia\
**Tags:** question\
**Created:** [August 22, 2020, 12:05pm UTC](https://discourse.julialang.org/t/understanding-the-notation-arr-1-2-arr2-5-7/45363 "2020-08-22T12:05:39Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![conditionality](https://avatars.discourse-cdn.com/v4/letter/c/4af34b/32.png) [@conditionality](https://discourse.julialang.org/u/conditionality)\
**Post date:** [August 22, 2020, 12:05pm UTC](https://discourse.julialang.org/t/understanding-the-notation-arr-1-2-arr2-5-7/45363/1 "2020-08-22T12:05:39Z")

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I’m came across a notation in the LibPQ.jl documentation:

```julia
LibPQ.load!(
    (no_nulls = ["foo", "baz"], yes_nulls = ["bar", missing]),
    conn,
    "INSERT INTO libpqjl_test (no_nulls, yes_nulls) VALUES (\$1, \$2);",
)

```

where (no\_nulls = [“foo”, “baz”], yes\_nulls = [“bar”, missing]) is used as an argument. Could you please explain what this notation means and how it works? I would have guessed it’s just a pair of two arrays, but looking into the LibPQ library ([https://github.com/invenia/LibPQ.jl/blob/master/src/tables.jl](https://github.com/invenia/LibPQ.jl/blob/master/src/tables.jl)) they call it a “table”, and I know there is something called Tables.jl (athough, I haven’t used it). Please help me understand. And how does it tie together to “$1” (which I can guess takes an elt from first array, but how does this really work)?

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**Author:** ![Tamas\_Papp](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/tamas_papp/32/25949_2.png) [@Tamas\_Papp](https://discourse.julialang.org/u/Tamas_Papp)\
**Post date:** [August 22, 2020, 12:25pm UTC](https://discourse.julialang.org/t/understanding-the-notation-arr-1-2-arr2-5-7/45363/2 "2020-08-22T12:25:56Z")

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[https://docs.julialang.org/en/v1/manual/types/#Named-Tuple-Types-1](https://docs.julialang.org/en/v1/manual/types/#Named-Tuple-Types-1)