Bradford assay

The following layout was used to measure the concentration of purified protein mutants using a Bradford assay. There are a few things worth noting for this example:

The same standard curve can be used for many experiments, so it makes sense to keep those concentrations in a separate file, to be included as necessary. Specifying these concentrations in a single place reduces redundancy and decreases the chance of making mistakes.
The wells in the standard curve layout are specified using block instead of row and col. This makes it safe to include the standard curve in other layouts, because the blocks won’t grow as more wells are added to the layout.
The [bradford] table provides information on how to parse the data. In particular, my lab has two different brands of plate reader, and they produce output in different formats, so the analysis script needs to know which format to expect. (The absorbance information is also needed to parse the data file, frustratingly, because the BioTek output format is ridiculous.) This information can be accessed in analysis scripts via the meta argument to load():
```
>>> import wellmap
>>> df, meta = wellmap.load('bradford_assay.toml', meta=True)
>>> meta.extras
{'bradford': {'format': 'biotek', 'absorbance': '595/450'}}
```

bradford_assay.toml

[meta]
include = 'bradford_standards.toml'

[bradford]
format = 'biotek'
absorbance = '595/450'

[block.3x2]
D1.sample  = 'Y37A'
D4.sample  = 'D42A'
D7.sample  = 'T44A'
D10.sample = 'Y45A'
F1.sample  = 'Y37E'
F4.sample  = 'T44P'
F7.sample  = 'Y45R'

[row]
'D,F'.dilution = 1
'E,G'.dilution = 5

bradford_standards.toml

[block.9x3.A1]
standard = true

# Pierce BCA Protein Assay Kit
# Catalog: Thermo #23225
# Manual: tinyurl.com/y8uj7dzy
[block.1x3]
A1.ug_mL = 2000
A2.ug_mL = 1500
A3.ug_mL = 1000
A4.ug_mL = 750
A5.ug_mL = 500
A6.ug_mL = 250
A7.ug_mL = 125
A8.ug_mL = 25
A9.ug_mL = 0