How to use the visidata.ColumnAttr function in visidata

if exc_val:
            self.thread.exception = exc_val
        else:
            # remove very-short-lived async actions
            if elapsed_s(self.thread) < min_thread_time_s:
                vd().threads.remove(self.thread)

class ProfileSheet(Sheet):
    columns = [
        Column('funcname', getter=lambda col,row: codestr(row.code)),
        Column('filename', getter=lambda col,row: os.path.split(row.code.co_filename)[-1] if not isinstance(row.code, str) else ''),
        Column('linenum', type=int, getter=lambda col,row: row.code.co_firstlineno if not isinstance(row.code, str) else None),

        Column('inlinetime_us', type=int, getter=lambda col,row: row.inlinetime*1000000),
        Column('totaltime_us', type=int, getter=lambda col,row: row.totaltime*1000000),
        ColumnAttr('callcount', type=int),
        Column('avg_inline_us', type=int, getter=lambda col,row: row.inlinetime*1000000/row.callcount),
        Column('avg_total_us', type=int, getter=lambda col,row: row.totaltime*1000000/row.callcount),
        ColumnAttr('reccallcount', type=int),
        ColumnAttr('calls'),
        Column('callers', getter=lambda col,row: col.sheet.callers[row.code]),
    ]

    nKeys=3

    def reload(self):
        self.rows = self.source
        self.orderBy(self.column('inlinetime_us'), reverse=True)
        self.callers = collections.defaultdict(list)  # [row.code] -> list(code)

        for r in self.rows:
            calls = getattr(r, 'calls', None)

if elapsed_s(self.thread) < min_thread_time_s:
                vd().threads.remove(self.thread)

class ProfileSheet(Sheet):
    columns = [
        Column('funcname', getter=lambda col,row: codestr(row.code)),
        Column('filename', getter=lambda col,row: os.path.split(row.code.co_filename)[-1] if not isinstance(row.code, str) else ''),
        Column('linenum', type=int, getter=lambda col,row: row.code.co_firstlineno if not isinstance(row.code, str) else None),

        Column('inlinetime_us', type=int, getter=lambda col,row: row.inlinetime*1000000),
        Column('totaltime_us', type=int, getter=lambda col,row: row.totaltime*1000000),
        ColumnAttr('callcount', type=int),
        Column('avg_inline_us', type=int, getter=lambda col,row: row.inlinetime*1000000/row.callcount),
        Column('avg_total_us', type=int, getter=lambda col,row: row.totaltime*1000000/row.callcount),
        ColumnAttr('reccallcount', type=int),
        ColumnAttr('calls'),
        Column('callers', getter=lambda col,row: col.sheet.callers[row.code]),
    ]

    nKeys=3

    def reload(self):
        self.rows = self.source
        self.orderBy(self.column('inlinetime_us'), reverse=True)
        self.callers = collections.defaultdict(list)  # [row.code] -> list(code)

        for r in self.rows:
            calls = getattr(r, 'calls', None)
            if calls:
                for callee in calls:
                    self.callers[callee.code].append(r)

c.sheet = self.source[0]
        return c

ColumnsSheet.addCommand(None, 'resize-source-rows-max', 'for c in selectedRows or [cursorRow]: c.width = c.getMaxWidth(source.visibleRows)')
ColumnsSheet.addCommand('&', 'join-cols', 'rows.insert(cursorRowIndex, combineColumns(selectedRows or fail("no columns selected to concatenate")))')


class SheetsSheet(Sheet):
    rowtype = 'sheets'
    precious = False
    columns = [
        ColumnAttr('name', width=30),
        ColumnAttr('nRows', type=int),
        ColumnAttr('nCols', type=int),
        ColumnAttr('nVisibleCols', type=int),
        ColumnAttr('cursorDisplay'),
        ColumnAttr('keyColNames'),
        ColumnAttr('source'),
        ColumnAttr('progressPct'),
    ]
    nKeys = 1

    def newRow(self):
        return Sheet('', columns=[ColumnItem('', 0)], rows=[])

    def reload(self):
        self.rows = self.source

SheetsSheet.addCommand(ENTER, 'open-row', 'dest=cursorRow; vd.sheets.remove(sheet) if not sheet.precious else None; vd.push(dest)')
SheetsSheet.addCommand('g'+ENTER, 'open-rows', 'for vs in selectedRows: vd.push(vs)')
SheetsSheet.addCommand('g^R', 'reload-selected', 'for vs in selectedRows or rows: vs.reload()')
SheetsSheet.addCommand('gC', 'columns-selected', 'vd.push(ColumnsSheet("all_columns", source=selectedRows or rows[1:]))')

SheetsSheet.addCommand('gI', 'describe-selected', 'vd.push(DescribeSheet("describe_all", source=selectedRows or rows[1:]))')

# source: vd.allSheets (with BaseSheet as weakref keys)
class GraveyardSheet(SheetsSheet):
    rowtype = 'undead sheets'  # rowdef: BaseSheet
    def reload(self):
        self.rows = list(vs for vs in self.source.keys() if vs not in vd().sheets)


class HelpSheet(Sheet):
    'Show all commands available to the source sheet.'
    rowtype = 'commands'
    precious = False

    columns = [
        ColumnAttr('sheet'),
        ColumnAttr('longname'),
        Column('keystrokes', getter=lambda col,row: col.sheet.revbinds.get(row.longname)),
        Column('description', getter=lambda col,row: col.sheet.cmddict[(row.sheet, row.longname)].helpstr),
        ColumnAttr('execstr', width=0),
        ColumnAttr('logged', 'replayable', width=0),
    ]
    nKeys = 2
    @asyncthread
    def reload(self):
        from pkg_resources import resource_filename
        cmdlist = TsvSheet('cmdlist', source=Path(resource_filename(__name__, 'commands.tsv')))
        cmdlist.reload_sync()
        self.cmddict = {}
        for cmdrow in cmdlist.rows:
            self.cmddict[(cmdrow.sheet, cmdrow.longname)] = cmdrow

self.addRow(r)

        # if an ordering has been specified, sort the sheet
        if self._ordering:
            vd.sync(self.sort())


class IndexSheet(Sheet):
    rowtype = 'sheets'
    precious = False

    columns = [
        ColumnAttr('name'),
        ColumnAttr('rows', 'nRows', type=int),
        ColumnAttr('cols', 'nCols', type=int),
        ColumnAttr('keys', 'keyColNames'),
        ColumnAttr('source'),
    ]
    nKeys = 1

    def newRow(self):
        return Sheet('', columns=[ColumnItem('', 0)], rows=[])

    def openRow(self, row):
        return row  # rowdef is Sheet

    def getSheet(self, k):
        for vs in self.rows:
            if vs.name == k:
                return vs

# add the rest of the rows
        for r in vd.Progress(itsource, gerund='loading', total=0):
            self.addRow(r)

        # if an ordering has been specified, sort the sheet
        if self._ordering:
            vd.sync(self.sort())


class IndexSheet(Sheet):
    rowtype = 'sheets'
    precious = False

    columns = [
        ColumnAttr('name'),
        ColumnAttr('rows', 'nRows', type=int),
        ColumnAttr('cols', 'nCols', type=int),
        ColumnAttr('keys', 'keyColNames'),
        ColumnAttr('source'),
    ]
    nKeys = 1

    def newRow(self):
        return Sheet('', columns=[ColumnItem('', 0)], rows=[])

    def openRow(self, row):
        return row  # rowdef is Sheet

    def getSheet(self, k):
        for vs in self.rows:
            if vs.name == k:
                return vs

return c

ColumnsSheet.addCommand(None, 'resize-source-rows-max', 'for c in selectedRows or [cursorRow]: c.width = c.getMaxWidth(source.visibleRows)')
ColumnsSheet.addCommand('&', 'join-cols', 'rows.insert(cursorRowIndex, combineColumns(selectedRows or fail("no columns selected to concatenate")))')


class SheetsSheet(Sheet):
    rowtype = 'sheets'
    precious = False
    columns = [
        ColumnAttr('name', width=30),
        ColumnAttr('nRows', type=int),
        ColumnAttr('nCols', type=int),
        ColumnAttr('nVisibleCols', type=int),
        ColumnAttr('cursorDisplay'),
        ColumnAttr('keyColNames'),
        ColumnAttr('source'),
        ColumnAttr('progressPct'),
    ]
    nKeys = 1

    def newRow(self):
        return Sheet('', columns=[ColumnItem('', 0)], rows=[])

    def reload(self):
        self.rows = self.source

SheetsSheet.addCommand(ENTER, 'open-row', 'dest=cursorRow; vd.sheets.remove(sheet) if not sheet.precious else None; vd.push(dest)')
SheetsSheet.addCommand('g'+ENTER, 'open-rows', 'for vs in selectedRows: vd.push(vs)')
SheetsSheet.addCommand('g^R', 'reload-selected', 'for vs in selectedRows or rows: vs.reload()')
SheetsSheet.addCommand('gC', 'columns-selected', 'vd.push(ColumnsSheet("all_columns", source=selectedRows or rows[1:]))')
SheetsSheet.addCommand('gI', 'describe-selected', 'vd.push(DescribeSheet("describe_all", source=selectedRows or rows[1:]))')

for vs in self.rows:
            if vs.name == k:
                return vs


class SheetsSheet(IndexSheet):
    columns = [
        ColumnAttr('name', width=30),
        ColumnAttr('shortcut'),
        ColumnAttr('nRows', type=int),
        ColumnAttr('nCols', type=int),
        ColumnAttr('nVisibleCols', type=int),
        ColumnAttr('cursorDisplay'),
        ColumnAttr('keyColNames'),
        ColumnAttr('source'),
        ColumnAttr('progressPct'),
#        ColumnAttr('threads', 'currentThreads', type=vlen),
    ]
    nKeys = 1
    def reload(self):
        self.rows = self.source


@VisiData.property
@drawcache
def _evalcontexts(vd):
    return {}

## VisiData sheet manipulation

@VisiData.global_api
def replace(vd, vs):

c = type(self.source[0])._coltype()
        c.sheet = self.source[0]
        return c

ColumnsSheet.addCommand(None, 'resize-source-rows-max', 'for c in selectedRows or [cursorRow]: c.width = c.getMaxWidth(source.visibleRows)')
ColumnsSheet.addCommand('&', 'join-cols', 'rows.insert(cursorRowIndex, combineColumns(selectedRows or fail("no columns selected to concatenate")))')


class SheetsSheet(Sheet):
    rowtype = 'sheets'
    precious = False
    columns = [
        ColumnAttr('name', width=30),
        ColumnAttr('nRows', type=int),
        ColumnAttr('nCols', type=int),
        ColumnAttr('nVisibleCols', type=int),
        ColumnAttr('cursorDisplay'),
        ColumnAttr('keyColNames'),
        ColumnAttr('source'),
        ColumnAttr('progressPct'),
    ]
    nKeys = 1

    def newRow(self):
        return Sheet('', columns=[ColumnItem('', 0)], rows=[])

    def reload(self):
        self.rows = self.source

SheetsSheet.addCommand(ENTER, 'open-row', 'dest=cursorRow; vd.sheets.remove(sheet) if not sheet.precious else None; vd.push(dest)')
SheetsSheet.addCommand('g'+ENTER, 'open-rows', 'for vs in selectedRows: vd.push(vs)')
SheetsSheet.addCommand('g^R', 'reload-selected', 'for vs in selectedRows or rows: vs.reload()')

def newRow(self):
        return Sheet('', columns=[ColumnItem('', 0)], rows=[])

    def openRow(self, row):
        return row  # rowdef is Sheet

    def getSheet(self, k):
        for vs in self.rows:
            if vs.name == k:
                return vs


class SheetsSheet(IndexSheet):
    columns = [
        ColumnAttr('name', width=30),
        ColumnAttr('shortcut'),
        ColumnAttr('nRows', type=int),
        ColumnAttr('nCols', type=int),
        ColumnAttr('nVisibleCols', type=int),
        ColumnAttr('cursorDisplay'),
        ColumnAttr('keyColNames'),
        ColumnAttr('source'),
        ColumnAttr('progressPct'),
#        ColumnAttr('threads', 'currentThreads', type=vlen),
    ]
    nKeys = 1
    def reload(self):
        self.rows = self.source


@VisiData.property